3-substituted 2,7-naphthyridin-1-yl derivatives

ABSTRACT

3-Substituted 2,7-naphthyridine derivatives of formula (1) are described:                    
     wherein 
     L 1  and L 1  is each a covalent bond or a linker atom or group; 
     Alk 1  is an optionally substituted aliphatic chain; 
     R 2  is a hydrogen atom or an optionally substituted heteroaliphatic, cycloaliphatic, heterocycloaliphatic, polycycloaliphatic, heteropolycycloaliphatic, aromatic or heteroaromatic group; 
     Alk is a chain                    
     in which R is a carboxylic acid (—CO 2 H) or a derivative or biostere thereof; 
     Ar 2  is an optionally substituted aromatic or heteroaromatic linking group; 
     R 16  is the group —L 3 (Alk 2 ) t L 4 R 20  in which L 3  and L 4  which may be the same or different is each a covalent bond or a linker atom or group, t is zero or the integer 1, Alk 2  is an optionally substituted aliphatic or heteroaliphatic chain and R 20  is an optionally substituted aromatic or heteroaromatic group; 
     and the salts, solvates, hydrates and N-oxides thereof. 
     The compounds are able to inhibit the binding of integrins to their ligands and are of use in the prophylaxis and treatment of immuno or inflammatory disorders or disorders involving the inappropriate growth or migration of cells.

This invention relates to a series of 3-substituted2,7-naphthyridin-1-yl derivatives, to compositions containing them, toprocesses for their preparation, and to their use in medicine.

Over the last few years it has become increasingly clear that thephysical interaction of inflammatory leukocytes with each other andother cells of the body plays an important role in regulating immune andinflammatory responses [Springer, T. A., Nature, 346, 425, (1990);Springer, T. A., Cell, 76, 301, (1994)]. Specific cell surface moleculescollectively referred to as cell adhesion molecules mediate many ofthese interactions.

The adhesion molecules have been sub-divided into different groups onthe basis of their structure. One family of adhesion molecules which isbelieved to play a particularly important role in regulating immune andinflammatory responses is the integrin family. This family of cellsurface glycoproteins has a typical non-covalently linked heterodimerstructure. At least 16 different integrin alpha chains and 8 differentintegrin beta chains have been identified [Newman, P. et al, MolecularMedicine Today, 304, (1996)]. The members of the family are typicallynamed according to their heterodimer composition although trivialnomenclature is widespread in the field. Thus the integrin α4β1 consistsof the integrin alpha 4 chain associated with the integrin beta 1 chain,but is also widely referred to as Very Late Antigen 4 or VLA-4. Not allof the potential pairings of integrin alpha and beta chains have yetbeen observed in nature and the integrin family has been subdivided intoa number of subgroups based on the pairings that have been recognised todate [Sonnenberg, A., Current Topics in Microbiology and Immunology,184, 7, (1993)].

The importance of integrin function in normal physiological responses ishighlighted by two human deficiency diseases in which integrin functionis defective. Thus in the disease termed Leukocyte Adhesion Deficiency(LAD) there is a defect in one of the families of integrins expressed onleukocytes [Marlin, S. D. et al, J. Exp. Med. 164, 855, (1986)].Patients suffering from this disease have a reduced ability to recruitleukocytes to inflammatory sites and suffer recurrent infections, whichin extreme cases may be fatal. In the case of patients suffering fromthe disease termed Glanzman's thrombasthenia (a defect in a member ofthe beta 3 integrin family) there is a defect in blood clotting(Hodivala-Dilke, K. M., J. Clin. Invest. 103, 229, (1999)].

The potential to modify integrin function in such a way as tobeneficially modulate cell adhesion has been extensively investigated inanimal models using specific antibodies and peptides that block variousfunctions of these molecules [e.g. Issekutz, T. B., J. Immunol. 149,3394, (1992); Li, Z. et al, Am. J. Physiol. 263, L723, (1992); Mitjans,F. et al, J. Cell Sci. 108, 2825, (1995); Brooks, P. C. et al, J. Clin.Invest. 96, 1815, (1995); Binns, R. M. et al, J. Immunol. 157, 4094,(1996); Hammes, H.-P. et al, Nature Medicine 2, 529, (1996); Srivata, S.et al, Cardiovascular Res. 36, 408 (1997)]. A number of monoclonalantibodies which block integrin function are currently beinginvestigated for their therapeutic potential in human disease, and one,ReoPro, a chimeric antibody against the platelet integrin αIIbβ3 is inuse as a potent anti-thrombotic agent for use in patients withcardiovascular complications following coronary angioplasty.

Integrins recognize both cell surface and extracellular matrix ligands,and ligand specificity is determined by the particular alpha-betasubunit combination of the molecule [Newman, P., ibid]. One particularintegrin subgroup of interest involves the α4 chain which can pair withtwo different beta chains β1 and β7 [Sonnenberg, A., ibid]. The α4β1pairing occurs on many circulating leukocytes (for example lymphocytes,monocytes, eosinophils and basophils) although it is absent or onlypresent at low levels on circulating neutrophils. α4β1 binds to anadhesion molecule (Vascular Cell Adhesion Molecule-1 also known asVCAM-1) frequently up-regulated on endothelial cells at sites ofinflammation [Osborne, L., Cell, 62, 3, (1990)]. The molecule has alsobeen shown to bind to at least three sites in the matrix moleculefibronectin [Humphries, M. J. et al, Ciba Foundation Symposium, 189,177, (1995)]. Based on data obtained with monoclonal antibodies inanimal models it is believed that the interaction between α4β1 andligands on other cells and the extracellular matrix plays an importantrole in leukocyte migration and activation [Yednock, T. A. et al,Nature, 356, 63, (1992); Podolsky, D. K. et al, J. Clin. Invest. 92,372, (1993); Abraham, W. M. et al, J. Clin. Invest. 93, 776, (1994)].

The integrin generated by the pairing of α4 and β7 has been termedLPAM-1 [Holzmann, B. and Weissman, I. L., EMBO J. 8, 1735, (1989)]. Theα4β7 pairing is expressed on certain sub-populations of T and Blymphocytes and on eosinophils [Erie, D. J. et al, J. Immunol. 153, 517(1994)]. Like α4β1, α4β7 binds to VCAM-1 and fibronectin. In addition,α4β7 binds to an adhesion molecule believed to be involved in the homingof leukocytes to mucosal tissue termed MAdCAM-1 [Berlin, C. et al, Cell,74, 185, (1993)]. The interaction between α4β7 and MAdCAM-1 may also beimportant sites of inflammation outside of mucosal tissue [Yang, X.-D.et al, PNAS, 91, 12604, (1994)].

Regions of the peptide sequence recognizeded by α4β1 and α4β7 when theybind to their ligands have been identified. α4β1 seems to recognise LDV,IDA or REDV peptide sequences in fibronectin and a QIDSP sequence inVCAM-1 [Humphries, M. J. et al, ibid] whilst α4β7 recognises a LDTsequence in MAdCAM-1 [Birskin, M. J. et al, J. Immunol. 156, 719,(1996)]. There have been several reports of inhibitors of theseinteractions being designed from modifications of these short peptidesequences [Cardarelli, P. M. et al, J. Biol. Chem., 269, 18668, (1994);Shorff, H. N. et al, Biorganic Med. Chem. Lett., 6, 2495, (1996);Vanderslice, P. et al, J. Immunol., 158, 1710, (1997)]. It has also beenreported that a short peptide sequence derived from the α4β1 bindingsite in fibronectin can inhibit a contact hypersensitivity reaction in atrinitrochlorobenzene sensitised mouse [Ferguson, T. A., et al, PNAS,88, 8072, (1991)].

Since the alpha 4 subgroup of integrins are predominantly expressed onleukocytes their inhibition can be expected to be beneficial in a numberof immune or inflammatory disease states. However, because of theubiquitous distribution and wide range of functions performed by othermembers of the integrin family it is important to be able to identifyselective inhibitors of the alpha 4 subgroup.

We have now found a group of 3-substituted 2,7-naphthyridinylderivatives which are potent and selective inhibitors of α4-integrins.Members of the group are able to inhibit α4 integrins such as α4β1 andα4β7 at concentrations at which they generally have no or minimalinhibitory action on α integrins of other subgroups. The 3-substituted2,7-naphthyridinyl derivatives show unexpectedly high inhibition ofα4-integrins when compared to unsubstituted 2,7-naphthyridinylderivatives. Additionally, the 3-substituted 2,7-naphthyridinylderivatives of the invention show a surprisingly improvedpharmacokinetic profile in comparison to unsubstituted2,7-naphthyridinyl derivatives, particularly improved bioavailability.The compounds are thus of use in medicine, for example in theprophylaxis and treatment of immune or inflammatory disorders asdescribed hereinafter.

Thus according to one aspect of the invention we provide a compound offormula (1):

wherein

R¹ is a hydrogen atom or a C₁₋₆alkyl group;

L¹ is a covalent bond or a linker atom or group;

Alk¹ is an optionally substituted aliphatic chain;

n is zero or the integer 1;

R² is a hydrogen atom or an optionally substituted heteroaliphatic,cycloaliphatic, heterocycloaliphatic, polycycloaliphatic,heteropolycycloaliphatic, aromatic or heteroaromatic group;

Alk is a chain

in which R is a carboxylic acid (—CO₂H) or a derivative or biosterethereof;

Ar² is an optionally substituted aromatic or heteroaromatic linkinggroup;

L² is a covalent bond or a linker atom or group;

R¹⁶ is the group —L³(Alk²)_(t)L⁴R²⁰ in which L³ and L⁴ which may be thesame or different is each a covalent bond or a linker atom or group, tis zero or the integer 1, Alk² is an optionally substituted aliphatic orheteroaliphatic chain and R²⁰ is an optionally substituted aromatic orheteroaromatic group;

g is zero or the integer 1, 2, 3 or 4;

each R¹⁷ which may be the same or different is a hydrogen or halogenatom or an optionally substituted straight or branched alkyl, alkoxy,alkylthio or cycloalkyl aromatic or heteroaromatic group or a thiol(—SH), hydroxyl (—OH), amino (—NH₂), —N(R³)(R⁴) [where R³ and R⁴ is eachindependently a hydrogen atom or an optionally substituted alkyl groupor together with the N atom to which they are attached the R³ and R⁴alkyl groups are joined to form a heterocyclic ring which may beoptionally interrupted by a further —O— or —S— heteroatom or —N(R³)—group], —CN, —CO₂R³, —NO₂, —CON(R³)(R⁴), —CSN(R³)(R⁴), —COR³,—N(R³)COR⁴, —N(R³)CSR⁴, —SO₂N(R³)(R⁴), —N(R³)SO₂R⁴, —N(R³)CON(R⁴)(R⁵)[where R⁵ is a hydrogen atom or an optionally substituted alkyl group ortogether with the N atom to which they are attached R⁴ and R⁵ alkylgroups are joined to form a heterocyclic ring which may be optionallyinterrupted by a further —O— or —S— heteroatom or —N(R³) group] or—N(R³)SO₂N(R⁴)(R⁵) group; and the salts, solvates, hydrates and N-oxidesthereof.

It will be appreciated that compounds of formula (1) may have one ormore chiral centers, and exist as enantiomers or diastereomers. Theinvention is to be understood to extend to all such enantiomers,diastereomers and mixtures thereof, including racemates. Formula (1) andthe formulae hereinafter are intended to represent all individualisomers and mixtures thereof, unless stated or shown otherwise. Inaddition, compounds of formula (1) may exist as tautomers, for exampleketo (CH₂C═O)-enol (CH═CHOH) tautomers. Formula (1) and the formulaehereinafter are intended to represent all individual tautomers andmixtures thereof, unless stated otherwise.

Optionally substituted aromatic and heteroaromatic groups represented byR²⁰ in the group —L³(Alk²)_(t)L⁴R²⁰ include those optionally substitutedaromatic and heteroaromatic groups as described hereinafter for thegroup R², for example C₆₋₁₂monocyclic aromatic groups or C₁₋₉monocyclicheteroaromatic groups. One, two or three optional substituents (R¹⁸)which may be the same or different that may be present on such R²⁰aromatic and heteroaromatic groups include those optional substituentsas described hereinafter for R² aromatic and heteroaromatic groups.

When L³ and/or L⁴ is present in these substituents as a linker atom orgroup it may be any divalent linking atom or group. Particular examplesinclude —O— or —S— atoms or —C(O)—, —C(O)O—, —OC(O)—, —C(S)—, —S(O)—,—S(O)₂—, —N(R⁸)— [where R⁸ is a hydrogen atom or an optionallysubstituted alkyl group], —N(R⁸)O—, —N(R⁸)N—, —CON(R⁸)—, —OC(O)N(R⁸)—,—CSN(R⁸)—, —N(R⁸)CO—, —N(R⁸)C(O)O—, —N(R⁸)CS—, —S(O)₂N(R⁸)—,—N(R⁸)S(O)₂—, —N(R⁸)CON(R⁸)—, —N(R⁸)CSN(R⁸)—, or —N(R⁸)SO₂N(R⁸)— groups.Where the linker group contains two R⁸ substituents, these may be thesame or different.

When R⁸ is present as an alkyl group it may be a straight or branchedC₁₋₆alkyl group, e.g. a C₁₋₃alkyl group such as a methyl or ethyl groupor a C₃₋₈cycloalkyl group particularly a C₃₋₆cycloalkyl group e.g. acyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl group. Optionalsubstituents which may be present on such groups include for exampleone, two or three substituents which may be the same or differentselected from halogen atoms, for example fluorine, chlorine, bromine oriodine atoms, or hydroxy or C₁₋₆alkoxy e.g. methoxy or ethoxy groups.

When Alk² is present as an aliphatic or heteroaliphatic chain it may befor example any divalent chain corresponding to the below-mentionedaliphatic chains described for Alk¹ or heteroaliphatic groups describedfor R² in which one of the terminal hydrogen atoms is replaced by abond.

Examples of the substituent represented by —L³(Alk²)_(t)L⁴R²⁰ which ispresent at the 3-position of the 2,7-naphthyridin-1-yl ring as the groupR¹⁶ in compounds of the invention include atoms or groups —L³Alk²L⁴R²⁰,—L³Alk²R²⁰, —L³R²⁰, —R²⁰ and -Alk²R²⁰ wherein L³, Alk², L⁴ and R²⁰ areas defined above. Particular examples of such substituents include—L³CH₂L⁴R²⁰, —L³CH(CH₃)L⁴R²⁰, —L³(CH₂)₂L⁴R²⁰, —L³CH₂R²⁰, —L³CH(CH₃)R²⁰,—L³(CH₂)₂R²⁰, —CH₂R²⁰, —CH(CH₃)R²⁰, —(CH₂)₂R²⁰ and —R²⁰ groups.

Particular examples of R²⁰ optionally substituted aromatic andheteroaromatic groups when present in the group —L³(Alk³)_(t)L⁴R²⁰include optionally substituted phenyl, furyl, thienyl, triazolyl,imidazolyl, pyridyl, pyrimidinyl, thiazolyl, oxazolyl, isoxazolyl,isothiazolyl, pyrazolyl and triazinyl groups.

Particular examples of R¹⁶ substituents represented by—L³(Alk²)_(t)L⁴R²⁰ in compounds of the invention include optionallysubstituted phenyl, furyl, thienyl, triazolyl, imidazolyl, pyridyl,pyrimidinyl, thiazolyl, oxazolyl, isoxazolyl, isothiazolyl, pyrazolyl,triazinyl, benzyl, furylmethyl, thienylmethyl, imidazolylmethyl,pyridylmethyl, pyrimidinylmethyl, benzyloxy, furylmethyloxy,thienylmethyloxy, imidazolylmethyloxy, pyridylmethyloxy,pyrimidinylmethyloxy, phenyloxy, furyloxy, thienyloxy, pyridyloxy,pyrimidinyloxy, phenylthio, furylthio, thienylthio, pyridylthio,pyrimidinylthio, phenylmethylthio, furylmethylthio, thienylmethylthio,pyridylmethylthio, pyrimidinylmethylthio, phenylamino, furylamino,thienylamino, pyridylamino. pyrimidinylamino, phenylmethylamino,furylmethylamino, thienylmethylamino, pyridylmethylamino,pyrimidinylmethylamino, N-methylphenylmethylamino,N-methylfurylmethylamino, N-methylthienylmethylamino,N-methylpyridylmethylamino, N-methylpyridinylmethylamino,phenylcarbonyl, furylcarbonyl, thienylcarbonyl, pyridylcarbonyl andpyrimidinylcarbonyl groups.

When the substituent R¹⁷ in compounds of formula (1) is an optionallysubstituted alkyl group it may be for example an optionally substitutedstraight or branched C₁₋₆alkyl group, e.g. an optionally substitutedmethyl, ethyl, propyl or isopropyl group. Optional substituents whichmay be present on R¹⁷ alkyl groups include those optional substituentsas described in relation to R² heteroaliphatic chains hereinafter.Particular examples of optionally substituted R¹⁷ alkyl groups include—CF₃, —CHF₂, —CH₂F, —CCl₃, —CHCl₂, —CH₂Cl, —CH₂OCH₃ and —CH₂OCH₂CH₃groups. When the substituent R¹⁷ is an optionally substituted alkoxygroup it may be a group —OR⁵, for example an optionally substitutedmethoxy, ethoxy, propoxy or isopropoxy group. Optional substituents thatmay be present include those just described for R¹⁷ alkyl groups.Particular examples of R¹⁷ optionally substituted alkoxy groups include—OCF₃, —OCHF₂, —OCHF, —OCCl₃, —OCHCl₂, —OCH₂Cl, —OCH₂OCH₃ and—OCH₂OCH₂CH₃ groups. When R¹⁷ is an optionally substituted alkylthiogroup it may be a group —SR⁵ for example, an optionally substitutedmethylthio, ethylthio or isopropylthio group. Optional substituentswhich may be present include those optional substituents as justdescribed for R¹⁷ alkyl groups. When R¹⁷ is an optionally substitutedcycloalkyl group it may be for example an optionally substitutedC₃₋₈cycloalkyl group, especially a C₃₋₆cycloalkyl group e.g. acyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl group. Optionalsubstituents which may be present include those optional substituentsjust described for R¹⁷ alkyl groups. When R¹⁷ is an optionallysubstituted aromatic or heteroaromatic group it may be any aromatic orheteroaromatic group as described hereinafter for the group R². Optionalsubstituents which may be present on R¹⁷ aromatic and heteroaromaticgroups include those optional substituents described for R² aromatic andheteroaromatic groups. Particular examples of optionally substitutedaromatic groups include optionally substituted phenyl, furyl, thienyl,pyridyl and pyrimidinyl groups.

When R³, R⁴ and/or R⁵ is present in R¹⁷ groups as an optionallysubstituted alkyl group it may be any optionally substituted alkyl groupas previously described for R⁸.

When the groups R³ and R⁴ or R⁴ and R⁵ are both optionally substitutedalkyl groups e.g. optionally substituted C₁₋₆alkyl groups these groupsmay be joined together with the N atom to which they are attached toform a heterocyclic ring. Such heterocyclic rings may be optionallyinterrupted by a further heteroatom selected from —O—, —S— or —N(R³)—.Particular examples of such heterocyclic rings include optionallysubstituted piperidinyl, morpholinyl, thiomorpholinyl, pyrrolidinyl,imidazolidinyl and piperazinyl rings.

Where desired, two R¹⁷ substituents may be linked together to form acyclic group such as a cyclic ether e.g. a C₁₋₆alkylenedioxy group suchas methylenedioxy or ethylenedioxy.

L² when present in compounds of the invention may be a linker atom orgroup L^(2a) or a linker group -Alk^(a)(L^(2a))_(y)—, where Alk^(a) isan optionally substituted aliphatic or heteroaliphatic chain aspreviously defined for Alk², L^(2a) is a covalent bond or a linker atomor group as described hereinbefore for L³, and y is zero or the integer1.

Optionally substituted aromatic or heteroaromatic linking groupsrepresented by Ar² include those aromatic or heteroaromatic groupsdescribed hereinafter in relation to R² aromatic or heteroaromaticgroups respectively where said groups become divalent linking groups,for example phenylene, pyridinylene or pyrimidinylene groups. Theoptional substituents which may be present on these groups include one,two, three or four optional substituents (R^(17a), R^(17b), R^(17c) andR^(17d)) where such substituents include those R¹⁷ optional substituentsdescribed hereinbefore.

When the group R is present in compounds of the invention as aderivative of a carboxylic acid it may be for example a carboxylic acidester or amide. Particular esters and amides include —CO₂Alk⁷ as definedhereinafter and —CONR³R⁴ [where R³ and R⁴ are as defined hereinbefore inrelation to R¹⁷] groups. When R is a biostere of a carboxylic acid itmay be for example a tetrazole or other acid such as phosphonic acid,phosphinic acid, sulphonic acid, sulphonic acid or boronic acid or anacylsulphonamide group.

Esters (—CO₂Alk⁷) and amide (—CONR³R⁴) derivatives of the carboxylicacid group (—CO₂H) in compounds of formula (1) may advantageously beused as prodrugs of the active compound. Such prodrugs are compoundswhich undergo biotransformation to the corresponding carboxylic acidprior to exhibiting their pharmacological effects and the inventionparticularly extends to prodrugs of the acids of formula (1). Suchprodrugs are well known in the art, see for example International PatentApplication No. WO00/23419, Bodor, N. (Alfred Benzon Symposium, 1982,17, 156-177), Singh, G. et al (J. Sci. Ind. Res., 1996, 55, 497-510) andBundgaard, H., (Design of Prodrugs, 1985, Elsevier, Amsterdam).

An Alk⁷ group which may be present in an esterified carboxyl grouprepresented by —CO₂Alk⁷ includes a straight or branched optionallysubstituted C₁₋₈alkyl group such as a methyl, ethyl, n-propyl, i-propyl,n-butyl, i-butyl, s-butyl or t-butyl group; an optionally substitutedC₂₋₈alkenyl group such as a propenyl e.g. 2-propenyl or butenyl e.g.2-butenyl or 3-butenyl group, an optionally substituted C₂₋₈alkynylgroup such as a ethynyl, propynyl e.g. 2-propynyl or butynyl e.g.2-butynyl or 3-butynyl group, an optionally substituted C₃₋₈cycloalkylgroup such as a cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl orcycloheptyl group; an optionally substituted C₃₋₈cycloalkylC₁₋₈alkylgroup such as a cyclopentylmethyl, cyclohexylmethyl or cyclohexylethylgroup; an optionally substituted C₃₋₈heterocycloalkylC₁₋₆alkyl groupsuch as a morpholinyl-N-ethyl, thiomorpholinyl-N-methyl,pyrrolidinyl-N-ethyl, pyrrolidinyl-N-propyl, piperidinyl-N-ethyl,pyrazolidinyl-N-methyl or piperazinyl-N-ethyl group; an optionallysubstituted C₁₋₆alkyloxyC₁₋₆alkyl group such as a methyloxyethyl orpropyloxyethyl group; an optionally substituted C₁₋₆alkylthioC₁₋₆alkylgroup such as an ethylthioethyl group; an optionally substitutedC₁₋₆alkylsulfinylC₁₋₆alkyl group such as an methylsulfinylethyl group;an optionally substituted C₁₋₆alkylsulfonylC₁₋₆alkyl group such as anmethylsulfonylmethyl group; an optionally substitutedC₃₋₈cycloalkyloxyC₁₋₆alkyl group such as a cyclohexyloxymethyl group; anoptionally substituted C₃₋₈cycloalkylthioC1-6alkyl group such as acyclopentylthiomethyl group; an optionally substitutedC₃₋₈cycloalkylsulfinylC₁₋₆alkyl group such as acyclopentylsulfinylmethyl group; an optionally substitutedC₃₋₈cyclo-alkylsulfonylC₁₋₆alkyl group such as acyclopentylsulfonylmethyl group; an optionally substitutedC₁₋₆alkyloxycarbonylC₁₋₆alkyl group such as isobutoxycarbonylpropylgroup; an optionally substituted C₁₋₆alkyloxycarbonylC₁₋₆alkenyl groupsuch as isobutoxycarbonylpentenyl group; an optionally substitutedC₁₋₆alkyloxycarbonyloxyC₁₋₆alkyl group such as anisopropoxycarbonyloxyethyl e.g a 1-(isopropoxycarbonyloxy) ethyl,2-(isopropoxycarbonyloxy)ethyl or ethyloxycarbonyloxymethyl group; anoptionally substituted C₁₋₆alkyloxycarbonyloxyC₁₋₆alkenyl group such asa isopropoxycarbonyloxybutenyl group, an optionally substitutedC₃₋₈cycloalkyloxycarbonyloxyC₁₋₆alkyl group such as acyclohexyloxycarbonyloxyethyl, e.g. a 2-(cyclohexyloxycarbonyloxy)ethylgroup, an optionally substituted N-di-C₁₋₈alkylaminoC₁₋₈alkyl group suchas a N-dimethylaminoethyl or N-diethylaminoethyl group; an optionallysubstituted N-C₆₋₁₂aryl-N-C₁₋₆alkylaminoC₁₋₆alkyl group such as aN-phenyl-N-methylaminomethyl group; an optionally substitutedN-di-C₁₋₈alkyl-carbamoylC₁₋₈alkyl group such as aN-diethylcarbamoylmethyl group; an optionally substitutedC₆₋₁₀arylC₁₋₆alkyl group such as an optionally substituted benzyl,phenylethyl, phenylpropyl, 1-naphthylmethyl or 2-naphthylmethyl group; aC₆₋₁₀aryl group such as an optionally substituted phenyl, 1-naphthyl or2-naphthyl group; a C₆₋₁₀aryloxyC₁₋₈alkyl group such as an optionallysubstituted phenyloxymethyl, phenyloxyethyl, 1-naphthyloxymethyl, or2-naphthyloxymethyl group; a C₆₋₁₂arylthioC₁₋₈alkyl group such as anoptionally substituted phenylthioethyl group; aC₆₋₁₂arylsulfinylC₁₋₈alkyl group such as an optionally substitutedphenylsulfinylmethyl group; a C₆₋₁₂arylsulfonylC₁₋₈alkyl group such asan optionally substituted phenylsulfonylmethyl group; an optionallysubstituted C₁₋₈alkanoyloxyC₁₋₈alkyl group, such as a acetoxymethyl,ethoxy-carbonyloxyethyl, pivaloyloxymethyl, propionyloxyethyl orpropionyl-oxypropyl group; an optionally substituted C₄₋₈imidoC₁₋₈alkylgroup such as a succinimidomethyl or phthalamidoethyl group; aC₆₋₁₂aroyloxyC₁₋₈alkyl group such as an optionally substitutedbenzoyloxyethyl or benzoyloxypropyl group or a triglyceride such as a2-substituted triglyceride e.g. a 1,3-di-C₁₋₈alkylglycerol-2-yl groupsuch as a 1,3-diheptylglycerol-2-yl group. Optional substituents whichmay be present on the Alk⁷ group include R_(13a) substituents asdescribed hereinafter.

It will be appreciated that in the forgoing list of Alk⁷ groups thepoint of attachment to the remainder of the compound of formula (1) isvia the last described part of the Alk⁷ group. Thus, for example amethoxyethyl group would be attached by the ethyl group, whilst amorpholinyl-N-ethyl group would be attached via the N-ethyl group.

It will be further appreciated that in the forgoing list of Alk⁷ groups,where not specifically mentioned, alkyl groups may be replaced byalkenyl or alkynyl groups where such groups are as hereinafter definedfor Alk¹ alkenyl or alkynyl chains where such chains contain anadditional terminal hydrogen atom Additionally these alkyl, alkenyl oralkynyl groups may optionally be interrupted by one, two or three linkeratoms or groups where such linker atoms and groups are as previouslydefined for L³.

When the group R¹ is present in compounds of the invention as aC₁₋₆alkyl group it may be for example a straight or branched C₁₋₆alkylgroup, e.g. a C₁₋₃alkyl group such as a methyl or ethyl group.

The linker atom or group represented by L¹ in compounds of formula (1)may be any linker atom or group as described above for the linker atomor group L³.

When the group Alk¹ is present in compounds of formula (1) as anoptionally substituted aliphatic chain it may be an optionallysubstituted C₁₋₁₀aliphatic chain. Particular examples include optionallysubstituted straight or branched chain C₁₋₆alkylene, C₂₋₆alkenylene, orC₂₋₆alkynylene chains.

Particular examples of aliphatic chains represented by Alk¹ includeoptionally substituted —CH₂—, —(CH₂)₂—, —CH(CH₃)CH₂—, —(CH₂)₂CH₂—,—(CH₂)₃CH₂—, —CH(CH₃)(CH₂)₂—, —CH₂CH(CH₃)CH₂—, —C(CH₃)₂CH₂—,—CH₂C(CH₃)₂CH₂—, —(CH₂)₂C(CH₃)₂CH₂—, —(CH₂)₄CH₂—, —(CH₂)₅CH₂—, —CHCH—,—CHCHCH₂—, —CH₂CHCH—, —CHCHCH₂CH₂—, —CH₂CHCHCH₂—, —(CH₂)₂CHCH—, —CC—,—CCCH₂—, —CH₂CC—, —CCCH₂CH₂—, —CH₂CCCH₂— or —(CH₂)₂CCH— groups.

Heteroaliphatic groups represented by the group R² in the compounds offormula (1) include the aliphatic chains just described for Alk¹ butwith each containing a further terminal hydrogen atom and additionallycontaining one, two, three or four heteroatoms or heteroatom-containinggroups. Particular heteroatoms or groups include atoms or groups L⁵where L⁵ is as defined above for L³ when L³ is a linker atom or group.Each L⁵ atom or group may interrupt the aliphatic group, or may bepositioned at its terminal carbon atom to connect the group to anadjoining atom or group. Particular examples include optionallysubstituted —L⁵CH₃, —CH₂L⁵CH₃, —L⁵CH₂CH₃, —CH₂L⁵CH₂CH₃, —(CH₂)₂L⁵CH₃,—(CH₂)₃L⁵CH₃, —L⁵(CH₂)₃CH₃ and —(CH₂)₂L⁵CH₂CH₃ groups.

The optional substituents which may be present on aliphatic chains orheteroaliphatic groups represented by Alk¹ and R² respectively includeone, two, three or more substituents where each substituent may be thesame or different and is selected from halogen atoms, e.g. fluorine,chlorine, bromine or iodine atoms, or —OH, —CO₂H, —CO₂R⁹, where R⁹ is analkyl group as defined above for R⁸, —CONHR⁹, —CON(R⁹)₂, —COCH₃,C₁₋₆alkoxy, e.g. methoxy or ethoxy, thiol, —S(O)R⁹, —S(O)₂R⁹,C₁₋₆alkylthio e.g. methylthio or ethylthio, amino or substituted aminogroups. Substituted amino groups include —NHR⁹ and —N(R⁹)₂ groups. Wheretwo R⁹ groups are present in any of the above substituents these may bethe same or different.

Optionally substituted cycloaliphatic groups represented by the group R²in compounds of the invention include optionally substitutedC₃₋₁₀cycloaliphatic groups. Particular examples include optionallysubstituted C₃₋₁₀cycloalkyl, e.g. C₃₋₇cycloalkyl or C₃₋₁₀cycloalkenyl,e.g C₃₋₇cycloalkenyl groups.

Optionally substituted heterocycloaliphatic groups represented by thegroup R² include optionally substituted C₃₋₁₀ heterocycloaliphaticgroups. Particular examples include optionally substitutedC₃₋₁₀heterocycloalkyl, e.g. C₃₋₇heterocycloalkyl, orC₃₋₁₀heterocycloalkenyl, e.g. C₃₋₇hetercycloalkenyl groups, each of saidgroups containing one, two, three or four heteroatoms orheteroatom-containing groups L⁵ as defined above.

Optionally substituted polycycloaliphatic groups represented by thegroup R² include optionally substituted C₇₋₁₀bi- or tricycloalkyl orC₇₋₁₀bi- or tricycloalkenyl groups. Optionally substitutedheteropolycycloaliphatic groups represented by the group R² include theoptionally substituted polycycloalkyl groups just described, but witheach group additionally containing one, two, three or four L⁵ atoms orgroups.

Particular examples of cycloaliphatic, polycycloaliphatic,heterocycloaliphatic and heteropolycycloaliphatic groups represented bythe group R² include optionally substituted cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, cycloheptyl, 2-cyclobuten-1-yl,2-cyclopenten-1-yl, 3-cyclopenten-1-yl, adamantyl, norbornyl,norbornenyl, tetrahydrofuranyl, pyrroline, e.g. 2- or 3-pyrrolinyl,pyrrolidinyl, pyrrolidinone, oxazolidinyl, oxazolidinone, dioxolanyl,e.g. 1,3-dioxolanyl, imidazolinyl, e.g. 2-imidazolinyl, imidazolidinyl,pyrazolinyl, e.g. 2-pyrazolinyl, pyrazolidinyl, pyranyl, e.g. 2- or4-pyranyl, piperidinyl, homopiperidinyl, heptamethyleneiminyl,piperidinone, 1,4-dioxanyl, morpholinyl, morpholinone, 1,4-dithianyl,thiomorpholinyl, piperazinyl, homopiperazinyl, 1,3,5-trithianyl,oxazinyl, e.g. 2H-1,3-, 6H-1,3-, 6H-1,2-, 2H-1,2- or 4H-1,4-oxazinyl,1,2,5-oxathiazinyl, isoxazinyl, e.g. o- or p-isoxazinyl, oxathiazinyl,e.g. 1,2,5 or 1,2,6-oxathiazinyl, or 1,3,5,-oxadiazinyl groups.

The optional substituents which may be present on the cycloaliphatic,polycycloaliphatic, heterocycloaliphatic or heteropolycycloaliphaticgroups represented by the group R² include one, two, three or moresubstituents each selected from halogen atoms, e.g. fluorine, chlorine,bromine or iodine atoms, or C₁₋₆alkyl, e.g. methyl or ethyl,haloC₁₋₆alkyl, e.g. halomethyl or haloethyl such as difluoromethyl ortrifluoromethyl, optionally substituted by hydroxyl, e.g. —C(OH)(CF₃)₂,C₁₋₆alkoxy, e.g. methoxy or ethoxy, haloC₁₋₆alkoxy, e.g. halomethoxy orhaloethoxy such as difluoromethoxy or trifluoromethoxy, thiol,C₁₋₆alkylthio e.g. methylthio or ethylthio, or —(Alk⁴)_(v)R¹⁰ groups inwhich Alk⁴ is a straight or branched C₁₋₃alkylene chain, v is zero or aninteger 1 and R¹⁰ is a —OH, —SH, —N(R¹¹)₂ (in which R¹¹ is an atom orgroup as defined herein for R⁸), —CN, —CO₂R¹¹, —NO₂, —CON(R¹¹)₂,—CSN(R¹¹)₂, —COR¹¹, —CSN(R¹¹)₂, —N(R¹¹)COR¹¹, —N(R¹¹)CSR¹¹, —SO₂N(R¹¹)₂,—N(R¹¹)SO₂R¹¹, —N(R¹¹)CON(R¹¹)₂, —N(R¹¹)CSN(R¹¹), N(R¹¹)SO₂N(R¹¹)₂ oroptionally substituted phenyl group. Where two R¹¹ atoms or groups arepresent in these substituents these may be the same or different.Optionally substituted phenyl groups include phenyl substituted by one,two or three of the R¹³ groups described below.

Particular examples of Alk⁴ chains include —CH₂—, —CH₂CH₂—, —CH₂CH₂CH₂—and —CH(CH₃)CH₂— chains.

Additionally, when the group R² is a heterocycloaliphatic groupcontaining one or more nitrogen atoms each nitrogen atom may beoptionally substituted by a group —(L⁶)_(p)(Alk⁵)_(q)R¹² in which L⁶ is—C(O)—, —C(O)O—, —C(S)—, —S(O)₂—, —CON(R¹¹)—, —CSN(R¹¹)— or SO₂N(R¹¹)—;p is zero or an integer 1; Alk⁵ is an optionally substituted aliphaticor heteroaliphatic chain; q is zero or an integer 1; and R¹² is ahydrogen atom or an optionally substituted cycloaliphatic,heterocycloaliphatic, polycycloaliphatic, heteropolycycloaliphatic,aromatic or heteroaromatic group.

Optionally substituted aliphatic or heteroaliphatic chains representedby Alk⁵ include those optionally substituted chains described above forAlk². Cycloaliphatic, heterocycloaliphatic, polycycloaliphatic orheteropolycycloaliphatic groups represented by R¹² include those groupsjust described for the group R². Optional substituents which may bepresent on these groups include those described above in relation toAlk¹ aliphatic chains. Optionally substituted aromatic or heteroaromaticgroups represented by R¹² include those optionally substituted R²aromatic and heteroaromatic groups as described hereinafter.

Optionally substituted aromatic groups represented by R² include forexample optionally substituted monocyclic or bicyclic fused ringC₆₋₁₂aromatic groups, such as phenyl, 1- or 2-naphthyl, 1- or2-tetrahydronaphthyl, indanyl or indenyl groups.

Optionally substituted heteroaromatic groups represented by the group R²include for example optionally substituted C₁₋₉heteroaromatic groupscontaining for example one, two, three or four heteroatoms selected fromoxygen, sulphur or nitrogen atoms. In general, the heteroaromatic groupsmay be for example monocyclic or bicyclic fused ring heteroaromaticgroups. Monocyclic heteroaromatic groups include for example five- orsix-membered heteroaromatic groups containing one, two, three or fourheteroatoms selected from oxygen, sulphur or nitrogen atoms. Bicyclicheteroaromatic groups include for example eight- to thirteen-memberedfused-ring heteroaromatic groups containing one, two or more heteroatomsselected from oxygen, sulphur or nitrogen atoms.

Particular examples of heteroaromatic groups of these types includepyrrolyl, furyl, thienyl, imidazolyl, N—C₁₋₆alkylimidazolyl, oxazolyl,isoxazolyl, thiazolyl, isothiazolyl, pyrazolyl, 1,2,3-triazolyl,1,2,4-triazolyl, 1,2,3-oxadiazolyl, 1,2,4-oxadiazolyl,1,2,5-oxadiazolyl, 1,3,4-oxadiazolyl, 1,3,4-thiadiazole, pyridyl,pyrimidinyl, pyridazinyl, pyrazinyl, 1,3,5-triazinyl, 1,2,4-triazinyl,1,2,3-triazinyl, benzofuryl, [2,3-dihydro]benzofuryl,[2,3-dihydro]benzothienyl, benzothienyl, benzotriazolyl, indolyl,isoindolyl, benzimidazolyl, imidazo[1,2-a]pyridyl, benzothiazolyl,benzoxazolyl, benzopyranyl, [3,4-dihydro]benzopyranyl, quinazolinyl,quinoxalinyl, naphthyridinyl, pyrido[3,4-b]pyridyl,pyrido[3,2-b]pyridyl, pyrido[4,3-b]-pyridyl, quinolinyl, isoquinolinyl,tetrazolyl, 5,6,7,8-tetrahydroquinolinyl,5,6,7,8-tetrahydroisoquinolinyl, and imidyl, e.g. succinimidyl,phthalimidyl, or naphthalimidyl such as 1,8-naphthalimidyl.

Optional substituents which may be present on the aromatic orheteroaromatic groups represented by the group R² include one, two,three or more substituents, each selected from an atom or group R¹³ inwhich R¹³ is —R^(13a) or -Alk⁶(R^(13a))_(m), where R^(13a) is a halogenatom, or an amino (—NH₂), substituted amino, nitro, cyano, amidino,hydroxyl (—OH), substituted hydroxyl, formyl, carboxyl (—CO₂H),esterified carboxyl, thiol (—SH), substituted thiol, —COR¹⁴ [where R¹⁴is an -Alk⁶(R^(13a))_(m), cycloaliphatic, heterocycloaliphatic, aryl orheteroaryl group], —CSR¹⁴, —SO₃H, —SOR¹⁴, —SO₂R¹⁴, —SO₃R¹⁴, —SO₂NH₂,—SO₂NHR¹⁴, SO₂N(R¹⁴)₂, —CONH₂, —CSNH₂, —CONHR¹⁴, —CSNHR¹⁴, —CON[R¹⁴]₂,—CSN(R¹⁴)₂, —N(R¹¹)SO₂R¹⁴, —N(SO₂R¹⁴)₂, —NH(R¹¹)SO₂NH₂, —N(R¹¹)SO₂NHR¹⁴,—N(R¹¹)SO₂N(R¹⁴)₂, —N(R¹¹)COR¹⁴, —N(R¹¹)CONH₂, —N(R¹¹)CONHR¹⁴,—N(R¹¹)CON(R¹⁴)₂, —N(R¹¹)CSNH₂, —N(R¹¹)CSNHR¹⁴, —N(R¹¹)CSN(R¹⁴)₂,—N(R¹¹)CSR¹⁴, —N(R¹¹)C(O)OR¹⁴, —SO₂NHet¹ [where —NHet¹ is an optionallysubstituted C₅₋₇cyclicamino group optionally containing one or moreother —O— or —S— atoms or —N(R¹¹)—, —C(O)—, —C(S)—, S(O) or —S(O)₂groups], —CONHet¹, —CSNHet¹, —N(R¹¹)SO₂NHet¹, —N(R¹¹)CONHet¹,—N(R¹¹)CSNHet¹, —SO₂N(R¹¹)Het² [where Het² is an optionally substitutedmonocyclic C₅₋₇carbocyclic group optionally containing one or more —O—or —S— atoms or —N(R¹¹)—, —C(O)— or —C(S)— groups], -Het²,—CON(R¹¹)Het², —CSN(R¹¹)Het², —N(R¹¹)CON(R¹¹)Het², —N(R¹¹)CSN(R¹¹)Het²,cycloaliphatic, heterocycloaliphatic, aryl or heteroaryl group; Alk⁶ isa straight or branched C₁₋₆alkylene, C₂₋₆alkenylene or C₂₋₆alkynylenechain, optionally interrupted by one, two or three —O— or —S— atoms or—S(O)_(n) [where n is an integer 1 or 2] or —N(R¹⁵)— groups [where R¹⁵is a hydrogen atom or C₁₋₆alkyl, e.g. methyl or ethyl group]; and m iszero or an integer 1, 2 or 3. It will be appreciated that when two R¹¹or R¹⁴ groups are present in one of the above substituents, the R¹¹ orR¹⁴ groups may be the same or different.

When in the group -Alk⁶(R^(13a))_(m) m is an integer 1, 2 or 3, it is tobe understood that the substituent or substituents R^(13a) may bepresent on any suitable carbon atom in -Alk⁶. Where more than oneR^(13a) substituent is present these may be the same or different andmay be present on the same or different atom in -Alk⁶. Clearly, when mis zero and no substituent R^(13a) is present the alkylene, alkenyleneor alkynylene chain represented by Alk⁶ becomes an alkyl, alkenyl oralkynyl group.

When R^(13a) is a substituted amino group it may be for example a group—NHR¹⁴ [where R¹⁴ is as defined above] or a group —N(R¹⁴)₂ wherein eachR¹⁴ group is the same or different.

When R^(13a) is a halogen atom it may be for example a fluorine,chlorine, bromine, or iodine atom.

When R^(13a) is a substituted hydroxyl or substituted thiol group it maybe for example a group —OR¹⁴ or a —SR¹⁴ or —SC(═NH)NH₂ grouprespectively.

Esterified carboxyl groups represented by the group R^(13a) includegroups of formula —CO₂Alk⁷ wherein Alk⁷ is a group as definedhereinbefore.

When Alk⁶ is present in or as a substituent it may be for example amethylene, ethylene, n-propylene, i-propylene, n-butylene, i-butylene,s-butylene, t-butylene, ethenylene, 2-propenylene, 2-butenylene,3-butenylene, ethynylene, 2-propynylene, 2-butynylene or 3-butynylenechain, optionally interrupted by one, two, or three —O— or —S— , atomsor —S(O)—, —S(O)₂— or —N(R⁹)— groups.

Cycloaliphatic or heterocycloaliphatic groups represented by the groupsR^(13a) or R¹⁴ include those optionally substituted C₃₋₁₀cycloaliphaticor C₃₋₁₀heterocycloaliphatic groups described above for R².

Aryl or heteroaryl groups represented by the groups R^(13a) or R¹⁴include mono- or bicyclic optionally substituted C₆₋₁₂aromatic orC₁₋₉heteroaromatic groups as described above for the group R². Thearomatic and heteroaromatic groups may be attached to the remainder ofthe compound of formula (1) by any carbon or hetero e.g. nitrogen atomas appropriate.

When —NHet¹ or -Het² forms part of a substituent R¹³ each may be forexample an optionally substituted pyrrolidinyl, pyrazolidinyl,piperazinyl, morpholinyl, thiomorpholinyl, piperidinyl or thiazolidinylgroup. Additionally Het² may represent for example, an optionallysubstituted cyclopentyl or cyclohexyl group. Optional substituents whichmay be present on —NHet¹ or -Het² include those optional substituentsdescribed above for R² heterocycloaliphatic groups.

Particularly useful atoms or groups represented by R¹³ include fluorine,chlorine, bromine or iodine atoms, or C₁₋₆alkyl, e.g. methyl, ethyl,n-propyl, i-propyl, n-butyl or t-butyl, optionally substituted phenyl,pyridyl, pyrimidinyl, pyrrolyl, furyl, thiazolyl, thienyl, morpholinyl,thiomorpholinyl, piperazinyl, e.g. t-butyloxycarbonylpiperazinyl,pyrrolidinyl, dioxolanyl, dioxanyl, oxazolidinyl, thiazolidinyl,imidazolidinyl or piperidinyl, C₁₋₆hydroxyalkyl, e.g. hydroxymethyl orhydroxyethyl, carboxyC₁₋₆alkyl, e.g. carboxyethyl, C₁₋₆alkylthio e.g.methylthio or ethylthio, carboxyC₁₋₆alkylthio, e.g. carboxymethylthio,2-carboxyethylthio or 3-carboxypropylthio, C₁₋₆alkoxy, e.g. methoxy orethoxy, hydroxyC₁₋₆alkoxy, e.g. 2-hydroxyethoxy, optionally substitutedphenoxy, pyridyloxy, thiazolyoxy, phenylthio or pyridylthio,C₄₋₇cycloalkyl, e.g. cyclobutyl, cyclopentyl, C₅₋₇cycloalkoxy, e.g.cyclopentyloxy, haloC₁₋₆alkyl, e.g. trifluoromethyl, haloC₁₋₆alkoxy,e.g. trifluoromethoxy, C₁₋₆alkylamino, e.g. methylamino, ethylamino orpropylamino, C₆₋₁₂arylC₁₋₆alkylamino, e.g.benzylamino,4-fluorobenzylamino or 4-hydroxyphenylethylamino, amino (—NH₂),aminoC₁₋₆alkyl, e.g. aminomethyl or aminoethyl, C₁₋₆dialkylamino, e.g.dimethylamino or diethylamino, aminoC₁₋₆alkylamino, e.g. aminoethylaminoor aminopropylamino, optionally substituted Het¹NC₁₋₆alkylamino, e.g.3-morpholinopropylamino, C₁₋₆alkylaminoC₁₋₆alkyl, e.g. ethylaminoethyl,C₁₋₆dialkylaminoC₁₋₆alkyl, e.g. diethylaminoethyl, aminoC₁₋₆alkoxy, e.g.aminoethoxy, C₁₋₆alkylaminoC₁₋₆alkoxy, e.g. methylaminoethoxy,C₁₋₆dialkylaminoC₁₋₆alkoxy, e.g. dimethylaminoethoxy,diethylaminoethoxy, diisopropylaminoethoxy, or dimethylaminopropoxy,hydroxyC₁₋₆alkylamino, e.g. 2-hydroxyethylamino, 3-hydroxypropylamino or3-hydroxybutylamino, imido, such as phthalimido or naphthalimido, e.g.1,8-naphthalimido, nitro, cyano, amidino, hydroxyl (—OH), formyl[HC(O)—], carboxyl (—CO₂H), —CO₂Alk⁷ [where Alk⁷ is as defined above],C₁₋₆alkanoyl e.g. acetyl, propyryl or butyryl, optionally substitutedbenzoyl, thiol (—SH), thioC₁₋₆alkyl, e.g. thiomethyl or thioethyl,—SC(═NH)NH₂, sulphonyl (—SO₃H), —SO₃Alk⁷, C₁₋₆alkylsulphinyl, e.g.methylsulphinyl, ethylsulphinyl or propylsulphinyl, C₁₋₆alkylsulphonyl,e.g. methylsulphonyl, ethylsulphonyl or propylsulphonyl, aminosulphonyl(—SO₂NH₂), C₁₋₆alkylaminosulphonyl, e.g. methylaminosulphonyl,ethylaminosulphonyl or propylaminosulphonyl C₁₋₆dialkylaminosulphonyl,e.g. dimethylaminosulphonyl or diethylaminosulphonyl,phenylaminosulphonyl, carboxamido (—CONH₂), C₁₋₆alkylaminocarbonyl, e.g.methylaminocarbonyl, ethylaminocarbonyl or propylaminocarbonyl,C₁₋₆dialkylaminocarbonyl, e.g. dimethylaminocarbonyl ordiethylaminocarbonyl, aminoC₁₋₆alkylaminocarbonyl, e.g.aminoethylaminocarbonyl, C₁₋₆alkylaminoC₁₋₆alkylaminocarbonyl, e.g.methylaminoethylaminocarbonyl, C₁₋₆dialkylaminoC₁₋₆alkylaminocarbonyl,e.g. diethylaminoethylaminocarbonyl, aminocarbonylamino,C₁₋₆alkylaminocarbonylamino, e.g. methylaminocarbonylamino orethylaminocarbonylamino, C₁₋₆dialkylaminocarbonylamino, e.g.dimethylaminocarbonylamino or diethylaminocarbonylamino,C₁₋₆alkylaminocabonylC₁₋₆alkylamino, e.g.methylaminocarbonylmethylamino, aminothiocarbonylamino,C₁₋₆alkylaminothiocarbonylamino, e.g. methylaminothiocarbonylamino orethylaminothiocarbonylamino, C₁₋₆dialkylaminothiocarbonylamino, e.g.dimethylaminothiocarbonylamino or diethylaminothiocarbonylamino,C₁₋₆alkylaminothiocarbonylC₁₋₆alkylamino, e.g.ethylaminothiocarbonylmethylamino, —CONHC(═NH)NH₂,C₁₋₆alkylsulphonylamino, e.g. methylsulphonylamino orethylsulphonylamino, haloC₁₋₆alkylsulphonylamino, e.g.trifluoromethylsulphonylamino, C₁₋₆dialkylsulphonylamino, e.g.dimethylsulphonylamino or diethylsulphonylamino, optionally substitutedphenylsulphonylamino, aminosulphonylamino (—NHSO₂NH₂),C₁₋₆alkylaminosulphonylamino, e.g. methylaminosulphonylamino orethylaminosulphonylamino, C₁₋₆dialkylaminosulphonylamino, e.g.dimethylaminosulphonylamino or diethylaminosulphonylamino, optionallysubstituted morpholinesulphonylamino ormorpholinesulphonylC₁₋₆alkylamino, optionally substitutedphenylaminosulphonylamino, C₁₋₆alkanoylamino, e.g. acetylamino,aminoC₁₋₆alkanoylamino e.g. aminoacetylamino,C₁₋₆dialkylaminoC₁₋₆alkanoylamino, e.g. dimethylaminoacetylamino,C₁₋₆alkanoylaminoC₁₋₆alkyl, e.g. acetylaminomethyl,C₁₋₆alkanoylaminoC₁₋₆alkylamino, e.g. acetamidoethylamino,C₁₋₆alkoxycarbonylamino, e.g. methoxycarbonylamino, ethoxycarbonylaminoor t-butoxycarbonylamino or optionally substituted benzyloxy,pyridylmethoxy, thiazolylmethoxy, benzyloxycarbonylamino,benzyloxycarbonylaminoC₁₋₆alkyl e.g. benzyloxycarbonylaminoethyl,thiobenzyl, pyridylmethylthio or thiazolylmethylthio groups.

Where desired, two R¹³ substituents may be linked together to form acyclic group such as a cyclic ether, e.g. a C₁₋₆alkylenedioxy group suchas methylenedioxy or ethylenedioxy.

It will be appreciated that where two or more R¹³ substituents arepresent, these need not necessarily be the same atoms and/or groups. Ingeneral, the substituent(s) may be present at any available ringposition in the aromatic or heteroaromatic group represented by R².

The presence of certain substituents in the compounds of formula (1) mayenable salts of the compounds to be formed. Suitable salts includepharmaceutically acceptable salts, for example acid addition saltsderived from inorganic or organic acids, and salts derived frominorganic and organic bases.

Acid addition salts include hydrochlorides, hydrobromides, hydroiodides,alkylsulphonates, e.g. methanesulphonates, ethanesulphonates, orisothionates, arylsulphonates, e.g. p-toluenesulphonates, besylates ornapsylates, phosphates, sulphates, hydrogen sulphates, acetates,trifluoroacetates, propionates, citrates, maleates, fumarates,malonates, succinates, lactates, oxalates, tartrates and benzoates.

Salts derived from inorganic or organic bases include alkali metal saltssuch as sodium or potassium salts, alkaline earth metal salts such asmagnesium or calcium salts, and organic amine salts such as morpholine,piperidine, dimethylamine or diethylamine salts.

Particularly useful salts of compounds according to the inventioninclude pharmaceutically acceptable salts, especially acid additionpharmaceutically acceptable salts.

In compounds according to the invention the group R¹⁶ is a—L³(Alk²)_(t)L⁴R²⁰ group. In compounds of this type R²⁰ is preferably anoptionally substituted aromatic group such as an optionally substitutedphenyl group or an optionally substituted monocyclic heteroaromaticgroup. Particularly useful monocyclic heteroaromatic groups areoptionally substituted five- or six-membered heteroaromatic groups aspreviously described, especially five- or six-membered heteroaromaticgroups containing one, two, three or four heteroatoms selected fromoxygen, sulphur or nitrogen atoms. Particularly useful optionalsubstituents that may be present on these R²⁰ groups include halogenatoms or optionally substituted alkyl, alkoxy, alkylthio, —NR³R⁴, —CN,—CO₂R³, —COR³ or —N(R³)COR⁴ groups, as described above in relation tothe compounds of formula (1).

In compounds of the invention Ar² is preferably an optionallysubstituted phenylene or pyridinediyl group. Most preferably Ar² is anoptionally substituted phenylene, especially 1,4-phenylene group.

A particularly useful group of compounds according to the invention hasthe formula (2):

wherein R^(17a) and R^(17b) is each a hydrogen atom or an optionalsubstituent as previously defined for R¹⁷;

and R¹⁶, R¹⁷, g, L¹, L², Ar², Alk, R¹, Alk¹, n and R² are as defined forformula (1);

and the salts, solvates, hydrates and N-oxides thereof.

Particularly useful optionally substituted monocyclic heteroaromaticgroups represented by R²⁰ in the group R¹⁶ include optionallysubstituted furyl, thienyl, imidazolyl, pyridyl and pyrimidinyl groups.Most especially useful R²⁰ aromatic groups include optionallysubstituted phenyl groups and most especially useful R²⁰ monocyclicheteroaromatic groups include thienyl and pyridyl groups.

In one preferred class of compounds of formula (2) R¹⁶ is the group—L³(Alk²)_(t)L⁴R²⁰ in which R²⁰ is preferably a group as just defined,L³ is preferably an —O— or —S— atom or a —C(O)— or —N(R⁸)— group inwhich R⁸ is preferably a hydrogen atom or a methyl group, t is theinteger 1 and Alk² is preferably an optionally substituted aliphaticchain, most preferably an optionally substituted C₁₋₆alkylene chain,especially an optionally substituted —CH₂—, —(CH₂)₂— or —CH(CH₃)CH₂—chain , and L⁴ is preferably a covalent bond.

In another preferred class of compounds of formula (2) R¹⁶ is the group—L³(Alk²)_(t)L⁴R²⁰ in which R²⁰ is preferably a group as just defined, tis zero and L³ and L⁴ is each a covalent bond.

Most particularly useful optional substituents which may be present onR²⁰ aromatic and heteroaromatic groups include halogen atoms, especiallyfluorine and chlorine atoms, and C₁₋₆alkyl groups, especially methyl,ethyl and i-propyl groups and —CF₃, —OCH₃, —OCH₂CH₃, —OCH(CH₃)₂, —OCF₃,—SCH₃, —NHCH₃, —N(CH₃)₂, —CN, —CO₂CH₃, —COCH₃ and —N(CH₃)COCH₃ groups.

Alk in compounds of the invention is preferably:

or, especially, —CH₂CH(R)—.

In one preferred class of compounds of formulae (1) and (2) R is a —CO₂Hgroup.

In another preferred class of compounds of formulae (1) and (2) R is anesterified carboxyl group of formula —CO₂Alk⁷. In this class of compoundAlk⁷ is preferably a C₁₋₈alkyl group, especially a methyl, ethyl,propyl, i-propyl or t-butyl group, an optionally substituted C₆₋₁₀arylgroup, especially a phenyl group, an optionally substitutedC₆₋₁₀arylC₁₋₆alkyl group, especially a benzyl group, aC₃₋₈heterocycloalkylC₁₋₆alkyl group, especially a morpholinyl-N-ethylgroup or a C₁₋₆alkyloxyC₁₋₆alkyl group, especially a methyloxyethylgroup. Especially preferred esterified carboxyl groups include —CO₂CH₃,—CO₂CH₂CH₃, —CO₂CH₂CH₂CH₃, —CO₂CH(CH₃)₂ and —CO₂C(CH₃)₃ groups.

In general in compounds of formulae (1) and (2) R¹ is preferably ahydrogen atom.

In general in compounds of formulae (1) and (2) L² is preferably L^(2a)where L^(2a) is an —O— atom or —N(R⁸)— group in which R⁸ is preferably ahydrogen atom or methyl group. R⁸ is most preferably a hydrogen atom.

In general in compounds of formula (2) R¹⁷, R^(17a) and R^(17b) whenpresent is each preferably independently chosen from a halogen atom,especially a fluorine or chlorine atom or an C₁₋₆alkyl, especially amethyl, ethyl, propyl or isopropyl group, a haloC₁₋₆alkyl group,especially —CF₃, a C₁₋₆alkoxy group especially methoxy, ethoxy, propoxyor isopropoxy or haloC₁₋₆alkoxy group, especially trifluoromethoxy ordifluoromethoxy, —CN, —COR³, especially —COCH₃, a C₁₋₆alkylthio group,especially methylthio or ethylthio, a C₃₋₈cycloalkyl group, especiallycyclopentyl or cyclohexyl or a C₁₋₆alkylenedioxy group, especially amethylenedioxy or ethylenedioxy group.

In one preferred class of compounds of formula (2) g is zero.

In another preferred class of compounds of formula (2) g is the integer1 or 2.

In general in compounds of formulae (1) and (2) when n is zero or theinteger 1 the group R² may especially be an optionally substitutedheteroaliphatic, cycloaliphatic, heterocycloaliphatic, aromatic orheteroaromatic group as defined herein. Particularly useful groups ofthis type include optionally substituted C₂₋₆heteroalkyl, particularlyC₁₋₃alkoxyC₁₋₃alkyl, especially methoxypropyl, optionally substitutedC₃₋₇cycloalkyl, especially optionally substituted cyclopropyl,cyclobutyl cyclopropyl or cyclohexyl, optionally substitutedC₅₋₇heterocycloaliphatic, especially optionally substitutedpyrrolidinyl, thiazolidinyl, pyrrolidinonyl, pipidinyl, homopiperidinyl,heptamethyleneiminyl. morpholinyl, piperazinyl or homopiperazinylgroups, C₆₋₁₂aromatic, especially optionally substituted phenyl groupsand optionally substituted C₅₋₇heteroaromatic, especially optionallysubstituted pyridyl groups. Optional substituents on these groupsinclude in particular R¹³ atoms or groups where the group is an aromaticor heteroaromatic group and —(L⁶)_(p)(Alk⁵)_(q)R¹² groups as describedearlier where the group is a nitrogen-containing heterocycloaliphaticgroup such as a pyrrolidinyl, thiazolidinyl, pyrrolidinonyl, pipidinyl,homopiperidinyl, heptamethyleneiminyl. morpholinyl, piperazinyl orhomopiperazinyl group. Particularly useful —(L⁶)_(p)(Alk⁵)_(q)R¹² groupsinclude those in which L⁶ is a —CO— group. Alk⁵ in these groups ispreferably present (i.e. q is preferably an integer 1) and in particularis a —CH₂-chain. Compounds of this type in which R¹² is a hydrogen atomor an optionally substituted aromatic or heteroaromatic group,especially an optionally substituted phenyl, pyridyl or imidazolyl groupare particularly preferred.

In one preferred class of compounds of formulae (1) and (2) L¹ ispresent as a —N(R⁸)— group. Particularly useful —N(R⁸)— groups include—NH—, —N(CH₃)—, —N(CH₂CH₃)— and —N(CH₂CH₂CH₃)— groups. In this class ofcompounds n is preferably the integer 1 and Alk¹ is preferably anoptionally substituted straight or branched C₁₋₆alkylene chain.Particularly useful Alk¹ chains include —CH₂—, —CH₂CH₂—, —CH₂CH₂CH₂—,—CH(CH₃)CH₂— and —C(CH₃)₂CH₂—. R² in this class of compounds ispreferably a hydrogen atom.

In another preferred class of compounds of formulae (1) and (2) L¹ is acovalent bond, n is the integer 1 and Alk¹ is an optionally substitutedstraight or branched C₁₋₆alkylene chain. Particularly useful Alk¹ chainsinclude optionally substituted —CH₂—, —CH₂CH₂—, —CH₂CH₂CH₂—,—CH(CH₃)CH₂— and especially —C(CH₃)₂CH₂— chains. R² in this class ofcompounds is preferably a hydrogen atom. A most especially usefuloptionally substituted Alk¹ R² group is —C(CH₃)₃.

In another preferred class of compounds of formulae (1) and (2), L¹ is acovalent bond, n is zero and R² is an optionally substitutedC₅₋₇heterocycloaliphatic group. Especially usefulC₅₋₇heterocycloaliphatic groups include optionally substitutedpiperidinyl, homopiperidinyl, heptamethyleneiminyl, pyrrolidinyl,piperazinyl, homopiperazinyl, morpholinyl and thiomorpholinyl groups.Most preferred C₅₋₇heterocycloaliphatic groups are those linked via aring nitrogen atom to the remainder of the compound of formulae (1) or(2). Most especially useful C₅₋₇heterocycloaliphatic groups includeoptionally substituted pyrolidin-1-yl, piperidin-1-yl andhomopiperidin-1-yl groups. Especially useful optional substituents onthese C₅₋₇heterocycloaliphatic groups include optionally substitutedC₁₋₆alkyl groups, especially methyl, ethyl or i-propyl groups. Mostpreferred optionally substituted C₅₋₇heterocycloaliphatic groups include2-methylpyrrolidin-1-yl, cis and trans 2,5-dimethylpyrrolidin-1-yl,2-methylpiperidin-yl and 2,6-dimethylpiperidin-1-yl, homopiperidin-1-yl,2-methylhomopiperidin-1-yl and cis and trans2,7-dimethylhomopiperidin-1-yl groups.

Particularly useful compounds of the invention include:

(S)-3-[4-(3-phenyl-2,7-naphthyridin-1-yloxy)phenyl]-2-[2-(azepan-1-yl)-3,4-dioxocyclobut-1-enylamino]propanoicacid;

and the salts, solvates, hydrates, N-oxides and carboxylic acid ester,particularly methyl, ethyl, propyl, I-propyl and t-butyl esters thereof.

Compounds according to the inventions are potent and selectiveinhibitors of α4 integrins and have advantageous clearance propertiesespecially those compounds where R is a carboxylic ester or amide. Theability of the compounds to act in this way may be simply determined byemploying tests such as those described in the Examples hereinafter.

The compounds are of use in modulating cell adhesion and in particularare of use in the prophylaxis and treatment of diseases or disordersinvolving inflammation in which the extravasation of leukocytes plays arole and the invention extends to such a use and to the use of thecompounds for the manufacture of a medicament for treating such diseasesor disorders.

Diseases or disorders of this type include inflammatory arthritis suchas rheumatoid arthritis vasculitis or polydermatomyositis, multiplesclerosis, allograft rejection, diabetes, inflammatory dermatoses suchas psoriasis or dermatitis, asthma and inflammatory bowel disease.

For the prophylaxis or treatment of disease the compounds according tothe invention may be administered as pharmaceutical compositions, andaccording to a further aspect of the invention we provide apharmaceutical composition which comprises a compound of formula (1)together with one or more pharmaceutically acceptable carriers,excipients or diluents.

Pharmaceutical compositions according to the invention may take a formsuitable for oral, buccal, parenteral, nasal, topical or rectaladministration, or a form suitable for administration by inhalation orinsufflation.

For oral administration, the pharmaceutical compositions may take theform of, for example, tablets, lozenges or capsules prepared byconventional means with pharmaceutically acceptable excipients such asbinding agents (e.g. pregelatinised maize starch, polyvinylpyrrolidoneor hydroxypropyl methylcellulose); fillers (e.g. lactose,microcrystalline cellulose or calcium hydrogen phosphate); lubricants(e.g. magnesium stearate, talc or silica); disintegrants (e.g. potatostarch or sodium glycollate); or wetting agents (e.g. sodium laurylsulphate). The tablets may be coated by methods well known in the art.Liquid preparations for oral administration may take the form of, forexample, solutions, syrups or suspensions, or they may be presented as adry product for constitution with water or other suitable vehicle beforeuse. Such liquid preparations may be prepared by conventional means withpharmaceutically acceptable additives such as suspending agents,emulsifying agents, non-aqueous vehicles and preservatives. Thepreparations may also contain buffer salts, flavouring, coloring andsweetening agents as appropriate.

Preparations for oral administration may be suitably formulated to givecontrolled release of the active compound.

For buccal administration the compositions may take the form of tabletsor lozenges formulated in conventional manner.

The compounds for formula (1) may be formulated for parenteraladministration by injection e.g. by bolus injection or infusion.Formulations for injection may be presented in unit dosage form, e.g. inglass ampoule or multi dose containers, e.g. glass vials. Thecompositions for injection may take such forms as suspensions, solutionsor emulsions in oily or aqueous vehicles, and may contain formulatoryagents such as suspending, stabilising, preserving and/or dispersingagents. Alternatively, the active ingredient may be in powder form forconstitution with a suitable vehicle, e.g. sterile pyrogen-free water,before use. For particle mediated administration the compounds offormula (1) may be coated on particles such as microscopic goldparticles.

In addition to the formulations described above, the compounds offormula (1) may also be formulated as a depot preparation. Such longacting formulations may be administered by implantation or byintramuscular injection.

For nasal administration or administration by inhalation, the compoundsfor use according to the present invention are conveniently delivered inthe form of an aerosol spray presentation for pressurised packs or anebuliser, with the use of suitable propellant, e.g.dichlorodifluoromethane, trichloro-fluoromethane,dichlorotetrafluoroethane, carbon dioxide or other suitable gas ormixture of gases.

The compositions may, if desired, be presented in a pack or dispenserdevice which may contain one or more unit dosage forms containing theactive ingredient. The pack or dispensing device may be accompanied byinstructions for administration.

The quantity of a compound of the invention required for the prophylaxisor treatment of a particular condition will vary depending on thecompound chosen, and the condition of the patient to be treated. Ingeneral, however, daily dosages may range from around 100 ng/kg to 100mg/kg e.g. around 0.01 mg/kg to 40 mg/kg body weight for oral or buccaladministration, from around 10 ng/kg to 50 mg/kg body weight forparenteral administration and around 0.05 mg to around 1000 mg e.g.around 0.5 mg to around 1000 mg for nasal administration oradministration by inhalation or insufflation.

The compounds of the invention may be prepared by a number of processesas generally described below and more specifically in the Exampleshereinafter. In the following process description, the symbols Ar², Alk,R¹, R², L¹, L², Alk¹ and n when used in the formulae depicted are to beunderstood to represent those groups described above in relation toformula (1) unless otherwise indicated. In the reactions describedbelow, it may be necessary to protect reactive functional groups, forexample hydroxy, amino, thio or carboxy groups, where these are desiredin the final product, to avoid their unwanted participation in thereactions. Conventional protecting groups may be used in accordance withstandard practice [see, for example, Green, T. W. in “Protective Groupsin Organic Synthesis”, John Wiley and Sons, 1999]. In some instances,deprotection may be the final step in the synthesis of a compound offormula (1) and the processes according to the invention describedhereinafter are to be understood to extend to such removal of protectinggroups. For convenience the processes described below all refer to apreparation of a compound of formula (1) but clearly the descriptionapplies equally to the preparation of compounds of formula (2).

Thus according to a further aspect of the invention, a compound offormula (1) in which R is a —CO₂H group may be obtained by hydrolysis ofan ester of formula (3):

where Ar¹ represents a group:

in which b signifies the point of attachment to the remainder of thecompound of formula (3);

and Alk represents a group

[where R^(y) is an alkyl group for example a C₁₋₆alkyl group]

The hydrolysis may be performed using either an acid or a base dependingon the nature of R^(y), for example an organic acid such astrifluoroacetic acid or an inorganic base such as lithium, sodium orpotassium hydroxide optionally in an aqueous organic solvent such as anamide e.g. a substituted amide such as dimethylformamide, an ether e.g.a cyclic ether such as tetrahydrofuran or dioxane or an alcohol e.g.methanol at a temperature from ambient to the reflux temperature. Wheredesired, mixtures of such solvents may be used.

According to a further aspect of the invention a compound of formula (1)may be prepared by displacement of a leaving group from a compound offormula (4):

where R^(a) is a leaving group, with an amine Ar¹L²Ar²AlkN(R¹)H or asalt thereof. Suitable leaving groups represented by R^(a) includehalogen atoms, especially chlorine and bromine atoms, or alkoxy, e.g.methoxy, ethoxy or isopropoxy, aryloxy, e.g. dinitrophenyloxy, oraralkoxy, e.g. benzyloxy, groups.

The reaction may be performed in an inert solvent or mixture ofsolvents, for example a substituted amide such as dimethylformamide, analcohol such as ethanol and/or a halogenated hydrocarbon such asdichloromethane, at a temperature from 0° C. to the reflux temperature.Where necessary, for example when a salt of an amine Ar¹L²Ar²AlkN(R¹)His used, an organic base such as diisopropylethylamine can be added.

Any carboxylic acid group present in the intermediate of formula (4) orthe amine Ar¹L²Ar²AlkN(R¹)H may need to be protected during thedisplacement reaction, for example as an ethyl ester. The desired acidmay then be obtained through subsequent hydrolysis, for example asparticularly described above and generally described below.

It will be appreciated that the displacement reaction may also beperformed on a compound of formula (5):

where R^(b) is a leaving group as defined for R^(a) using anintermediate R²(Alk¹)_(n)L¹H where —L¹H is a functional group such as anamine (—NH₂) using the reaction conditions just described.

Where desired the displacement reaction may also be performed on anintermediate of formulae (4) or (5), Ar¹L²Ar²AlkN(R¹)H orR²(Alk¹)_(n)L¹H which is linked, for example via its Ar¹, R or R² group,to a solid support, such as a polystyrene resin. After the reaction thedesired compound of formula (1) may be displaced from the support by anyconvenient method, depending on the original linkage chosen.

Intermediates of formulae (4) and (5) are either readily available ormay be prepared from an intermediate of formula (6):

where R^(a) and R^(b) are as previously defined and an amineAr¹L²Ar²AlkN(R¹)H or R²(Alk¹)^(n)N(R⁸)H by displacement as justdescribed for the preparation of compounds of formula (1).

Intermediates of formulae Ar¹L²Ar²AlkN(R¹)H and R²(Alk¹)_(n)N(R⁸)H maybe obtained from simpler, known compounds by one or more standardsynthetic methods employing substitution, oxidation, reduction orcleavage reactions. Particular substitution approaches includeconventional alkylation, arylation, heteroarylation, acylation,thioacylation, halogenation, sulphonylation, nitration, formylation andcoupling procedures. It will be appreciated that these methods may alsobe used to obtain or modify other compounds of formulae (1) and (2)where appropriate functional groups exist in these compounds.

Thus compounds of the invention and intermediates thereto may beprepared by alkylation, arylation or heteroarylation. For example,compounds containing a —L¹H or —L²H group (where L¹ and L² is each alinker atom or group) may be treated with a coupling agentR²(Alk¹)_(n)X¹ or Ar¹X¹ respectively in which X¹ is a leaving atom orgroup such as a halogen atom, e.g. a fluorine, bromine, iodine orchlorine atom or a sulphonyloxy group such as an alkylsulphonyloxy, e.g.trifluoromethylsulphonyloxy or arylsulphonyloxy, e.g.p-toluenesulphonyloxy group.

The reaction may be carried out in the presence of a base such as acarbonate, e.g. caesium or potassium carbonate, an alkoxide, e.g.potassium t-butoxide, or a hydride, e.g. sodium hydride, or an organicamine e.g. triethylamine or N,N-diisopropylethylamine or a cyclic amine,such as N-methylmorpholine or pyridine, in a dipolar aprotic solventsuch as an amide, e.g. a substituted amide such as dimethylformamide oran ether, e.g. a cyclic ether such as tetrahydrofuran.

Intermediates of formula Ar¹X¹ and R²(Alk¹)_(n)X¹ are generally known,readily available compounds or may be prepared from known compounds bystandard substitution and other synthetic procedures, for example asdescribed herein. Thus for example compounds of formula Ar¹X¹ in whichAr¹ represents a 3-substituted 2,7-naphthyridin-1-yl group may beprepared from alcohols of formula Ar¹OH by reaction with a halogenatingagent, for example a phosphorous oxyhalide such as phosphorousoxychloride at an elevated temperature e.g. 110° C.

Intermediate alcohols of formula Ar¹OH in which Ar¹ represents anoptionally substituted 2,7-naphthyridin-1-yl group may be prepared bymethods well known to a person skilled in the art, e.g. by the method ofSakamoto,T. et al [Chem. Pharm. Bull. 33, 626-633, (1985)] or Baldwin,J, J. et al [J. Org. Chem, 43, 4878-4880, (1978)]. Thus for example themethod of Baldwin may be modified to allow the synthesis of intermediate3-substituted 2,7-naphthyridin-1-yl groups of formula Ar¹ OH as depictedin Scheme 1:

Thus reaction of an optionally substituted 4-methyl-3-cyano pyridine offormula (7) with a N,N-dimethylformamide di-C₁₋₆alkyl acetal, e.g.N,N-dimethylformamide diethyl acetal, in a dipolar solvent such as anamide e.g. a substituted amide such as dimethylformamide at an elevatedtemperature e.g. 140-150° gives a compound of formula (8) or (9) or amixture thereof depending on the nature of the group R¹⁶.

Compounds of formula (8) or (9) may be cyclised to 3-substituted2,7-naphthyridin-1-yl alcohols of formula (10) by treatment with an acide.g. an inorganic acid such as hydrochloric acid or hydrobromic acid oran acidic gas such as hydrogen chloride gas in an organic solvent e.g.an organic acid such as acetic acid optionally in the presence of waterat a temperature from about ambient to 50° C.

Alternatively alkylating agents of formula Ar¹X¹ in which Ar¹ representsan optionally substituted 3-substituted 2,7-naphthyridin-yl group may beprepared by reaction of a 3-substituted 2,7-naphthyridine N-oxide orN,N′-dioxide with a halogenating agent, e.g. a phosphorous oxyhalidesuch as phosphorous oxychloride to give a 1-halo or 1,6-dihalo-and/or-1,8-dihalo-2,7-napthyridine respectively. In the case of1,6-dihalo- and/or 1,8-dialo-2,6-napthyridines each halogen atom may besubstituted separately by a reagent such as HL²Ar²AlkN(R¹)H orHN(R³)(R⁴) by the particular methods just described above.

3-Substituted 2,7-napthyridine N-oxides and N,N′-dioxides may begenerated from the corresponding 3-substituted 2,7-napthyridines by thegeneral methods of synthesis of N-oxides described below or they may besynthesised by the methods of Numata, A. et al (Synthesis, 1999,306-311).

Further alkylating agents of formula Ar¹X¹ in which, for example, Ar¹represents a 3-substituted 2,7-naphthyridin-1-yl, may be prepared by themethods of Wenkert E. et al J. Am. Chem. Soc. 89, 6741-5 (1967), andAust. J. Chem. 433 (1972), and Sheffield D. J. J. Chem. Soc. Perkin.Trans I, 2506 (1972).

In a further example intermediates of formula Ar¹L²Ar²AlkN(R¹)H may beobtained by reaction of a compound of formula Ar¹L²H with a compound offormula X¹Ar²AlkN(R¹)H under the reaction conditions just described.

Compounds of formula Ar¹L²H in which, for example Ar¹ represents a3-substituted 2,7-naphthyridin-1-yl group and L² is a —N(R⁸)— group, maybe prepared from substituted 4-formylpyridines by the methods of Molina,P. et al Tetrahedron, 48, 4601-4616, (1992), or by the methods describedin U.S. Pat. No. 3,938,367.

In another example, compounds containing a —L¹H or —L²H or group asdefined above may be functionalised by acylation or thioacylation, forexample by reaction with one of the alkylating agents just described butin which X¹ is replaced by a —C(O)X², C(S)X², —N(R⁸)COX² or —N(R⁸)C(S)X²group in which X² is a leaving atom or group as described for X¹. Thereaction may be performed in the presence of a base, such as a hydride,e.g. sodium hydride or an amine, e.g. triethylamine orN-methylmorpholine, in a solvent such as a halogenated hydrocarbon, e.g.dichloromethane or carbon tetrachloride or an amide, e.g.dimethylformamide, at for example ambient temperature. Alternatively,the acylation may be carried out under the same conditions with an acid(for example one of the alkylating agents described above in which X¹ isreplaced by a —CO₂H group) in the presence of a condensing agent, forexample a diimide such as 1-(3-dimethylaminopropyl)-3-ethylcarbodiimideor N,N′-dicyclohexylcarbodiimide, advantageously in the presence of acatalyst such as a N-hydroxy compound e.g. a N-hydroxytriazole such as1-hydroxybenzotriazole. Alternatively the acid may be reacted with achloroformate, for example ethylchloroformate, prior to the desiredacylation reaction

In a further example compounds may be obtained by sulphonylation of acompound containing an —OH group by reaction with one of the abovealkylating agents but in which X¹ is replaced by a —S(O)Hal or —SO₂Halgroup in which Hal is a halogen atom such as chlorine atom] in thepresence of a base, for example an inorganic base such as sodium hydridein a solvent such as an amide, e.g. a substituted amide such asdimethylformamide at for example ambient temperature.

In another example, compounds containing a —L¹ H or —L²H group asdefined above may be coupled with one of the alkylation agents justdescribed but in which X¹ is replaced by an —OH group in a solvent suchas tetrahydrofuran in the presence of a phosphine, e.g.triphenylphosphine and an activator such as diethyl, diisopropyl- ordimethylazodicarboxylate.

In a further example, ester groups —CO₂R³, —CO₂R¹¹ or —CO₂Alk⁷ in thecompounds may be converted to the corresponding acid [—CO₂H] by acid- orbase-catalysed hydrolysis depending on the nature of the groups R³, R¹¹or Alk⁷. Acid- or base-catalysed hydrolysis may be achieved for exampleby treatment with an organic or inorganic acid, e.g. trifluoroaceticacid in an aqueous solvent or a mineral acid such as hydrochloric acidin a solvent such as dioxan or an alkali metal hydroxide, e.g. lithiumhydroxide in an aqueous alcohol, e.g. aqueous methanol.

In a further example, —OR⁵ or —OR¹⁴ groups [where R⁵ or R¹⁴ eachrepresents an alkyl group such as methyl group] in compounds of formula(1) may be cleaved to the corresponding alcohol —OH by reaction withboron tribromide in a solvent such as a halogenated hydrocarbon, e.g.dichloromethane at a low temperature, e.g. around −78° C.

Alcohol [—OH] groups may also be obtained by hydrogenation of acorresponding —OCH₂R¹⁴ group (where R¹⁴ is an aryl group) using a metalcatalyst, for example palladium on a support such as carbon in a solventsuch as ethanol in the presence of ammonium formate, cyclohexadiene orhydrogen, from around ambient to the reflux temperature. In anotherexample, —OH groups may be generated from the corresponding ester [CO₂R³or CO₂R¹¹] or aldehyde [—CHO] by reduction, using for example a complexmetal hydride such as lithium aluminium hydride or sodium borohydride ina solvent such as methanol.

In another example, alcohol —OH groups in the compounds may be convertedto a corresponding —OR⁵ or —OR¹⁴ group by coupling with a reagent R⁵OHor R¹⁴OH in a solvent such as tetrahydrofuran in the presence of aphosphine, e.g. triphenylphosphine and an activator such as diethyl-,diisopropyl-, or dimethylazodicarboxylate.

Aminosulphonylamino [—NHSO₂NHR² or —NHSO₂NHAr¹] groups in the compoundsmay be obtained, in another example, by reaction of a correspondingamine [—NH₂] with a sulphamide R²NHSO₂NH₂ or Ar¹ NHSO₂NH₂ in thepresence of an organic base such as pyridine at an elevated temperature,e.g. the reflux temperature.

In another example compounds containing a —NHCSAr¹, —CSNHAr¹, —NHCSR² or—CSNHR² may be prepared by treating a corresponding compound containinga —NHCOAr¹, —CONHAr¹, —NHCOR² or —CONHR² group with a thiation reagent,such as Lawesson's Reagent, in an anhydrous solvent, for example acyclic ether such as tetrahydrofuran, at an elevated temperature such asthe reflux temperature.

In a further example amine (—NH₂) groups may be alkylated using areductive alkylation process employing an aldehyde and a borohydride,for example sodium triacetoxyborohyride or sodium cyanoborohydride, in asolvent such as a halogenated hydrocarbon, e.g. dichloromethane, aketone such as acetone, or an alcohol, e.g. ethanol, where necessary inthe presence of an acid such as acetic acid at around ambienttemperature.

In a further example, amine [—NH₂] groups in compounds of formula (1)may be obtained by hydrolysis from a corresponding imide by reactionwith hydrazine in a solvent such as an alcohol, e.g. ethanol at ambienttemperature.

In another example, a nitro [—NO₂] group may be reduced to an amine[—NH₂], for example by catalytic hydrogenation using for examplehydrogen in the presence of a metal catalyst, for example palladium on asupport such as carbon in a solvent such as an ether, e.g.tetrahydrofuran or an alcohol e.g. methanol, or by chemical reductionusing for example a metal, e.g. tin or iron, in the presence of an acidsuch as hydrochloric acid.

Aromatic halogen substituents in the compounds may be subjected tohalogen-metal exchange with a base, for example a lithium base such asn-butyl or t-butyl lithium, optionally at a low temperature, e.g. around−78° C., in a solvent such as tetrahydrofuran and then quenched with anelectrophile to introduce a desired substituent. Thus, for example, aformyl group may be introduced by using dimethylformamide as theelectrophile; a thiomethyl group may be introduced by usingdimethyldisulphide as the electrophile.

In another example, sulphur atoms in the compounds, for example whenpresent in a linker group L¹ or L² may be oxidised to the correspondingsulphoxide or sulphone using an oxidising agent such as a peroxy acid,e.g. 3-chloroperoxybenzoic acid, in an inert solvent such as ahalogenated hydrocarbon, e.g. dichloromethane, at around ambienttemperature.

In another example compounds of formula Ar¹X¹ (where X¹ is a halogenatom such as a chlorine, bromine or iodine atom) may be converted tosuch compounds as Ar¹CO₂R²⁰ (in which R²⁰ is an optionally substitutedalkyl, aryl or heteroaryl group), Ar¹CHO, Ar¹CHCHR²⁰, Ar¹CCR²⁰,Ar¹N(R²⁰)H, Ar¹N(R²⁰)₂, for use in the synthesis of for examplecompounds of formula Ar¹L²Ar²AlkN(R¹)H, using such well know andcommonly used palladium mediated reaction conditions as are to be foundin the general reference texts Rodd's Chemistry of Carbon Compounds,Volumes 1-15 and Supplementals (Elsevier Science Publishers, 1989),Fieser and Fieser's Reagents for Organic Synthesis, Volumes 1-19 (JohnWiley and Sons, 1999), Comprehensive Heterocyclic Chemistry, Ed.Katritzky et al, Volumes 1-8, 1984 and Volumes 1-11, 1994 (Pergamon),Comprehensive Organic Functional Group Transformations, Ed. Katritzky etal, Volumes 1-7, 1995 (Pergamon), Comprehensive Organic Synethesis, Ed.Trost and Flemming, Volumes 1-9, (Pergamon, 1991), Encyclopedia ofReagents for Organic Synthesis, Ed. Paquette, Volumes 1-8 (John Wileyand Sons, 1995), Larock's Comprehensive Organic Transformations (VCHPublishers Inc., 1989) and March's Advanced Organic Chemistry (JohnWiley and Sons, 2001).

N-oxides of compounds of formula (1) may be prepared for example byoxidation of the corresponding nitrogen base using an oxidising agentsuch as hydrogen peroxide in the presence of an acid such as aceticacid, at an elevated temperature, for example around 70° C. to 80° C.,or alternatively by reaction with a peracid such as peracetic acid in asolvent, e.g. dichloromethane, at ambient temperature.

Salts of compounds of formula (1) may be prepared by reaction of acompound of formula (1) with an appropriate base in a suitable solventor mixture of solvents e.g. an organic solvent such as an ether e.g.diethylether, or an alcohol, e.g. ethanol using conventional procedures.

Where it is desired to obtain a particular enantiomer of a compound offormula (1) this may be produced from a corresponding mixture ofenantiomers using any suitable conventional procedure for resolvingenantiomers.

Thus for example diastereomeric derivatives, e.g. salts, may be producedby reaction of a mixture of enantiomers of formula (1) e.g. a racemate,and an appropriate chiral compound, e.g. a chiral base. Thediastereomers may then be separated by any convenient means, for exampleby crystallisation and the desired enantiomer recovered, e.g. bytreatment with an acid in the instance where the diastereomer is a salt.

In another resolution process a racemate of formula (1) may be separatedusing chiral High Performance Liquid Chromatography. Alternatively, ifdesired a particular enantiomer may be obtained by using an appropriatechiral intermediate in one of the processes described above.

Chromatography, recrystallisation and other conventional separationprocedures may also be used with intermediates or final products whereit is desired to obtain a particular geometric isomer of the invention.

The following Examples illustrate the invention. All temperatures are in0° C. The following abbreviations are used:

NMM N-methylmorpholine; EtOAc—ethyl acetate; MeOH - methanol; BOC -butoxycarbonyl; DCM - dichloromethane; AcOH - acetic acid; DIPEA -diisopropylethylamine; EtOH - ethanol; Pyr - pyridine; Ar - aryl; DMSO -dimethylsulphoxide; iPr - isopropyl; Et₂O - diethylether; Me - methyl;THF - tetrahydrofuran, DMF - N,N-dimethylform- amide; EMOC -9-fluorenylmethoxycarbonyl; TFA - trifluoroacetic acid; All NMR's wereobtained at 300 mHz, unless otherwise indicated.

Intermediate 1

3-Cyano-4-(2-dimethylamino-2-phenylethylen-1-yl)pyridine

A solution of 3-cyano-4-methylpyridine (3.23 g, 27.4 mmol) andN,N-dimethylbenzyamide dimethyl acetal [prepared according to Hanessionet al: Can. J. Chem. 50, 233, (1972)]; (5.88 g, 30.2 mmol) in dry DMFwas stirred at 130° for 30 h. The volatiles were evaporated in vacuo andthe obtained oil chromatographed (silica; 50% EtOAc/Hexane) affordingthe title compound contaminated with 30% 3-cyano-4-methylpyridine. Thelatter was removed by evaporation under high vacuum at 80° affordingpure title compound as a yellow crystalline solid (2.49 g, 36%). δH(CDCl₃) 8.48 (1H, s), 7.86 (1H, d, J 5.9 Hz), 7.49-7.43 (3H, m),7.28-7.24 (2H, m), 5.85 (1H, d, J 5.9 Hz), 5.57 (1H, s) and 2.91 (6H,s); m/z (ES⁺, 70V) 250 (MH⁺).

Intermediate 2

1-Chloro-3-phenyl-2,7-naphthyridine

HCl gas was bubbled through a warmed solution of Intermediate 1 (3.49 g,14.0 mmol) in glacial acetic acid (35 ml) for about 2 min. The reactionflask was stoppered and the reaction mixture was stirred at 40° for 6 hand at room temperature for 18 h. The volatiles were removed in vacuo toafford a yellow solid which was treated with saturated aqueous NaHCO₃(50 ml). The obtained light yellow powder was collected by filtration,washed with water and dried to afford a mixture of1-hydroxy-3-phenyl-2,7-naphthyridine and the title compound (2.58 g, 2:1ratio). This mixture was treated with phosphorus oxychloride (30 ml) at130° for 7 h. The volatiles were removed in vacuo and the obtainedyellow solid partitioned (with CARE) between EtOAC (150 ml) and ice-coldsaturated aqueous NaHCO₃ (50 ml+5 g solid NaHCO₃). The phases wereseparated and the aqueous layer re-extracted with EtOAc (2×50 ml). Thecombined organic extracts were washed with brine (10 ml), dried (Na₂SO₄)and evaporated in vacuo to afford a dull yellow solid (2.5 g).Chromatography (silica: 1:1:2-2:1:1 EtOAc/DCM/Hexane) afforded the titlecompound as a pale yellow solid (2.21 g, 51% over two steps). δH (CDCl₃)9.74 (1H, s), 8.81 (1H, d, J 5.7 Hz), 8.17 (1H, d, J 8.0 Hz), 7.99 (1H,s), 7.70 (1H, d, J 5.7 Hz), 7.60-7.49 (3H, m); m/z (ES⁺, 70V) 241 and243 (MH⁺).

Intermediate 3

Ethyl(S)-3-[4-(3-phenyl-2,7-naphthyridin-1-yloxy)phenyl]-2-[-N-(t-butyloxycarbonyl)amino]propanoate

A mixture of N-(t-butyloxycarbonyl)tyrosine ethyl ester (1.48 g, 4.79mmol), Intermediate 2 (1.0 g, 4.16 mmol) and caesium carbonate (1.49 g,4.58 mmol) was stirred at room temperature for 2 days. The reactionmixture was diluted with Et₂O (100 ml) and the insoluble materialseparated by filtration. The filtrate was evaporated in vacuo and theobtained oil chromatographed (silica; 40 to 60% EtOAc/Hexane) affordingthe title compound as a colorless glass (2.0 g, 94%). δH (CDCl₃) 9.78(1H, s), 8.76 (1H, d, J 5.8 Hz), 7.93 (2H, d, J 8.4 Hz), 7.74 (1H, s),7.66 (1H, d, J 5.8 Hz), 7.46-7.36 (3H, m), 7.34-7.26 (4H, m), 5.13 (1H,d, J 8.0 Hz), 4.66 (1H, m), 4.19 (2H, q, J 7.1 Hz), 3.20 (2H, br d, J5.5 Hz), 1.46 (9H, s) and 1.26 (3H, t, J 7.1 Hz); m/z (ES⁺, 70V) 514(MH⁺).

Intermediate 4

Ethyl(S)-3-[4-(3-phenyl-2,7-naphthyridin-1-yloxy)phenyl]-2-aminopropanoate

HCl gas was bubbled through a solution of Intermediate 3 (2.0 g) inEtOAc (50 ml) for about 1 min, then the reaction mixture was stirred atambient temperature for 15 min. The volatiles were removed in vacuo andthe pale yellow solid partitioned between EtOAc (100 ml) and saturatedaqueous NaHCO₃ (50 ml). The phases were separated and the aqueous phasewas re-extracted with EtOAc (2×50 ml). The combined organic extractswere washed with brine (10 ml), dried (Na₂SO₄) and evaporated in vacuoto afford the title compound as a near colorless viscous oil (1.6 g,quart.). δH (CDCl₃) 9.69 (1H, s), 8.67 (1H, d, J 5.7 Hz), 7.84 (2H, d, J8.5 Hz), 7.64 (1H, s), 7.56 (1H, d, J 5.7 Hz), 7.38-7.27 (3H, m), 7.24(4H, m), 4.12 (2H, q, J 7.1 Hz), 3.71 (1H, dd, J 7.5, 5.5 Hz), 3.08 (1H,dd, J 13.5, 5.5 Hz), 2.90 (1H, dd, J 13.5, 7.5 Hz), 1.53 (2H, br s) and1.18 (3H, t, J 7.1 Hz); m/z (ES⁺, 70V) 414 (MH⁺).

Intermediate 5

Ethyl(S)-3-[4-(3-phenyl-2,7-naphthyridin-1-ylamino)phenyl]-2-[N-(t-butyloxycarbonyl)amino]propanoate

Acetylchloride (20 mg, 18 μl , 0.25 mmol) was added to absolute ethanol(10 ml), stirred for one minute, and then Intermediate 2 (1.20 g, 5.00mmol) and (S)-4-aminophenylalanine ethyl ester (1.54 g, 5.00 mmol) wereadded. The reaction mixture was stirred under reflux for 3 days. Thevolatiles were removed in vacuo and the obtained dull yellow solidchromatographed (silica: 1:1 EtOAc/Hexane-EtOAc) afforded the titlecompound as a yellow solid (1.7 g, 55%). δH (CDCl₃) 9.40 (1H, s), 8.66(1H, d, J 5.7 Hz), 8.13 (2H, d, J 8.4 Hz), 7.81 (2H, d, J 8.4 Hz), 7.59(1H, d, J 5.7 Hz), 7.54-7.42 (5H, m), 7.22 (2H, d, J 8.4 Hz), 5.09 (1H,br d, J 8.1 Hz), 4.60 (1H, m), 4.21 (2H, q, J 7.1 Hz), 3.15-3.12 (2H,m), 1.45 (9H, s) and 1.28 (3H, t, J 7.1 Hz); m/z (ES⁺, 70V) 513 (MH⁺).

EXAMPLE 1 Ethyl(S)-3-[4-(3-phenyl-2,7-naphthyridin-1-yloxy)phenyl]-2-[2-ethoxy-3,4-dioxocyclobut-1-enylamino]propanoate

A solution of Intermediate 4 (1.55 g, 3.75 mmol) and1,2-diethoxy-3,4-dioxocyclobut-1-ene (0.70 g, 4.11 mmol) in absoluteethanol (30 ml) was stirred at room temperature for 18 h. The volatileswere removed in vacuo and the obtained solid chromatographed (silica;1:1:2 Hexane/DCM/EtOAc-EtOAc) to afford the title compound as a whitefoam (1.99 g, 99%). δH (CDCl₃) 9.71 (1H, s), 8.66 (1H, d, J 5.9 Hz),7.86-7.83 (2H, m), 7.69 (1H, s), 7.68-7.64 (1H, m), 7.40-7.33 (3H, m),7.28-7.24 (1H, m), 7.20-7.14 (3H, m), 6.31 and 5.86 (together 1H, br s),5.13 and 4.61 (together 1H, br s), 4.67 (2H, q, J 7.0 Hz), 4.19 (2H, q,J 7.1 Hz), 3.20 (2H, br m), 1.37 (3H, t, J 7.0 Hz) and 1.22 (3H, t, J7.1 Hz); m/z (ES⁺, 70V) 538 (MH⁺).

EXAMPLE 2 Ethyl(S)-3-[4-(3-phenyl-2,7-naphthyridin-1-yloxy)phenyl]-2-[2-(azepan-1-yl)-3,4-dioxocyclobut-1-enylamino]propanoate

A solution of the compound of Example 1 (0.99 g, 1.84 mmol) andazepane(0.20 g, 2.02 mmol) in DCM (10 ml) and absolute ethanol (10 ml)was stirred at room temperature for 18 h. The volatiles were removed invacuo affording a white solid. Chromatography (silica; 75% EtOAc/Hexaneto 100% EtOAc; applied in DCM) afforded the title compound as a whitesolid (1.05 g, 97%). δH (CDCl₃) 9.78 (1H, s), 8.77 (1H, d, J 5.7 Hz),7.90 (2H, d, J 8.5 Hz), 7.74 (1H, s), 7.67 (1H, d, J 5.7 Hz), 7.47-7.37(3H, m), 7.38-7.22 (4H, m), 5.52-.5.35 (2H, m), 4,30 (2H, q, J 7.1 Hz),4.02-3.76 (2H, br m), 3.43 (1H, dd, J 14.1, 3.8 Hz), 3.35 (1H, dd, J14.1, 5.3 Hz), 3.40-3.21 (2H, br m), 1.85-1.64 (2H, br m), 1.70-1.48(6H, br m) and 1.35 (3H, t, J 7.1 Hz); m/z (ES⁺70V) 591 (MH⁺).

EXAMPLE 3(S)-3-[4-(3-Phenyl-2,7-naphthyridin-1-yloxy)phenyl]-2-[2-(azepan-1-yl)-3,4-dioxocyclobut-1-enylamino]propanoicacid

A solution of the compound of Example 2 (610 mg, 1.03 mmol) and LiOH.H₂O(65 mg, 1.55 mmol) in dioxan (5 ml) and water (8 ml) was stirred at roomtemperature for 1.5 h. A few drops of AcOH was added and the volatilesremoved in vacuo. The residue was chromatographed [silica; DCM (200),MeOH (20), AcOH (3), H₂O (2)] to afford the title compound as a paleyellow solid (430 mg, 74%). δH (DMSO-d⁶) 9.44 (1H, s), 8.57 (1H, d, J5.7 Hz), 7.92 (1H, s), 7.70-7.66 (3H, m), 7.49 (1H, d, J 9.1 Hz),7.21-7.09 (7H, m), 4.87 (1H, m), 3.70-3.15 (4H, br m), 3.22 (1H, dd, J13.8, 3.9 Hz), 2.99 (1H, dd, J 13.8, 11.1 Hz), 1.49-1.25 (4H, br m) and1.25-1.10 (4H, br m); m/z (ES⁺, 70V) 563 (MH⁺).

The following assays can be used to demonstrate the potency andselectivity of the compounds according to the invention. In each ofthese assays an IC₅₀ value was determined for each test compound andrepresents the concentration of compound necessary to achieve 50%inhibition of cell adhesion where 100%=adhesion assessed in the absenceof the test compound and 0%=absorbance in wells that did not receivecells.

α₄β₁ Integrin-dependent Jurkat Cell Adhesion to VCAM-Ig

96 well NUNC plates were coated with F(ab)₂ fragment goat anti-human IgGFcγ-specific antibody [Jackson Immuno Research 109-006-098: 100 μl at 2μg/ml in 0.1M NaHCO₃, pH 8.4], overnight at 40. The plates were washed(3×) in phosphate-buffered saline (PBS) and then blocked for 1 h inPBS/1% BSA at room temperature on a rocking platform. After washing (3×in PBS) 9 ng/ml of purified 2d VCAM-Ig diluted in PBS/1% BSA was addedand the plates left for 60 minutes at room temperature on a rockingplatform. The plates were washed (3× in PBS) and the assay thenperformed at 37° for 30 min in a total volume of 200 μl containing2.5×10⁵ Jurkat cells in the presence or absence of titrated testcompounds.

Each plate was washed (2×) with medium and the adherent cells were fixedwith 100 μl methanol for 10 minutes followed by another wash. 100 μl0.25% Rose Bengal (Sigma R4507) in PBS was added for 5 minutes at roomtemperature and the plates washed (3×) in PBS. 100 μl 50% (v/v) ethanolin PBS was added and the plates left for 60 min after which theabsorbance (570 nm) was measured.

α₄β₇ Integrin-dependent JY Cell Adhesion to MAdCAM-Ig

This assay was performed in the same manner as the α₄β₁ assay exceptthat MAdCAM-Ig (150 ng/ml) was used in place of 2d VCAM-Ig and asub-line of the β-lympho blastoid cell-line JY was used in place ofJurkat cells. The IC₅₀ value for each test compound was determined asdescribed in the α₄β₁ integrin assay.

α₅β₁ Integrin-dependent K562 Cell Adhesion to Fibronectin

96 well tissue culture plates were coated with human plasma fibronectin(Sigma F0895) at 5 μg/ml in phosphate-buffered saline (PBS) for 2 hr at37° C. The plates were washed (3× in PBS) and then blocked for 1 h in100 μl PBS/1% BSA at room temperature on a rocking platform. The blockedplates were washed (3× in PBS) and the assay then performed at 37° C. ina total volume of 200 μl containing 2.5×10⁵ K562 cells,phorbol-12-myristate-13-acetate at 10 ng/ml, and in the presence orabsence of titrated test compounds. Incubation time was 30 minutes. Eachplate was fixed and stained as described in the α₄β₁ assay above.

α_(m)β₂-dependent Human Polymorphonuclear Neutrophils Adhesion toPlastic

96 well tissue culture plates were coated with RPMI 1640/10% FCS for 2 hat 37° C. 2×10⁵ freshly isolated human venous polymorphonuclearneutrophils (PMN) were added to the wells in a total volume of 200 μl inthe presence of 10 ng/ml phorbol-12-myristate-13-acetate, and in thepresence or absence of test compounds, and incubated for 20 min at 37°C. followed by 30 min at room temperature. The plates were washed inmedium and 100 μl 0.1% (w/v) HMB (hexadecyl trimethyl ammonium bromide,Sigma H5882) in 0.05M potassium phosphate buffer, pH 6.0 added to eachwell. The plates were then left on a rocker at room temperature for 60min. Endogenous peroxidase activity was then assessed using tetramethylbenzidine (TMB) as follows: PMN lysate samples mixed with 0.22% H₂O₂(Sigma) and 50 μg/ml TMB (Boehringer Mannheim) in 0.1M sodiumacetate/citrate buffer, pH 6.0 and absorbance measured at 630 nm.

αIIb/β₃-dependent Human Platelet Aggregation

Human platelet aggregation was assessed using impedance aggregation onthe Chronolog Whole Blood Lumiaggregometer. Human platelet-rich plasma(PRP) was obtained by spinning fresh human venous blood anticoagulatedwith 0.38% (v/v) tri-sodium citrate at 220×g for 10 min and diluted to acell density of 6×10⁸ /ml in autologous plasma. Cuvettes contained equalvolumes of PRP and filtered Tyrode's buffer (g/liter: NaCl 8.0;MgCl₂.H₂O 0.427; CaCl₂ 0.2; KCl 0.2; D-glucose 1.0; NaHCO₃ 1.0;NaHPO₄.2H₂O 0.065). Aggregation was monitored following addition of 2.5μM ADP (Sigma) in the presence or absence of inhibitors.

In the above assays the preferred compounds of the invention such as thecompounds of the Examples generally have IC₅₀ values in the α₄β₁ andα₄β₇ assays of 1 μM and below. In the other assays featuring α integrinsof other subgroups the same compounds had IC₅₀ values of 50 μM and abovethus demonstrating the potency and selectivity of their action againstα₄ integrins.

The advantageous clearance properties (improved bioavailability) ofcompounds according to the invention may be demonstrated as follows:

Hepatic clearance, whether metabolic or biliary, can make a substantialcontribution to the total plasma clearance of a drug. The total plasmaclearance is a principal parameter of the pharmacokinetic properties ofa medicine. It has a direct impact on the dose required to achieveeffective plama concentrations and has a major impact on the eliminationhalf-life and therefore the dose-interval. Furthermore, high hepaticclearance is an indicator of high first-pass hepatic clearance afteroral administration and therefore low oral bioavailability.

Many peptidic and non-peptidic carboxylic acids of therapeutic interestare subject to high hepatic clearance from plasma. Except for drugswhich function in the liver, hepatic uptake from blood or plasma isundesirable because it leads to high hepatic clearance if the compoundis excreted in bile or metabolised, or if the substance is not clearedfrom the liver, it may accumulate in the liver and interfere with thenormal function of the liver.

The total plasma clearance of a compound according to the invention canbe determined as follows. A small dose of the compound in solution isinjected into a vein of a test animal. Blood samples are withdrawn froma blood vessel of the animal at several times after the injection, andthe concentration of compound in the bleed or plasma is measured using asuitable assay. The area under the curve (AUCiv) is calculated bynon-compartmental methods (for example, the trapezium method) or bypharmacokinetic modelling. The total plasma clearance (CL_(p)) iscalculated by dividing the intravenous dose(D_(iv)) by the AUC_(iv) forthe blood plasma concentration—time course of a drug administered by theintravenous route: CL_(p)=D_(iv)÷AUC_(iv).

When tested in this manner, compounds according to the invention are notrapidly or extensively extracted by the liver and have low total plasmaclearance where low is defined as less than 10 ml/min/kg in thelaboratory rat (Sprague Dawley CD). This compares favourably withfunctionally equivalent integrin binding compounds in which the squaricacid framework and/or the carboxylic ester or amide R group of compoundsof formula (1) is not present.

What is claimed is:
 1. A compound of formula (1):

wherein R¹ is a hydrogen atom or a C₁₋₆alkyl group; L¹ is a covalentbond or a linker atom or group; Alk¹ is an optionally substitutedaliphatic chain; n is zero or the integer 1; R² is a hydrogen atom or anoptionally substituted heteroaliphatic, cycloaliphatic,heterocycloaliphatic, polycycloaliphatic, heteropolycycloaliphatic,aromatic or heteroaromatic group; Alk is a chain

 in which R is a carboxylic acid (—CO₂H) or a derivative or biosterethereof; Ar² is an optionally substituted aromatic or heteroaromaticlinking group; L² is a covalent bond or a linker atom or group; R¹⁶ isthe group —L³(Alk²)_(t)L⁴R²⁰ in which L³ and L⁴ which may be the same ordifferent is each a covalent bond or a linker atom or group, t is zeroor the integer 1, Alk² is an optionally substituted aliphatic orheteroaliphatic chain and R²⁰ is an optionally substituted aromatic orheteroaromatic group; g is zero or the integer 1, 2, 3 or 4; each R¹⁷which may be the same or different is a hydrogen or halogen atom or anoptionally substituted straight or branched alkyl, alkoxy, alkylthio orcycloalkyl aromatic or heteroaromatic group or a thiol (—SH), hydroxyl(—OH), amino (—NH₂), —N(R³)(R⁴) [where R³ and R⁴ is each independently ahydrogen atom or an optionally substituted alkyl group or together withthe N atom to which they are attached the R³ and R⁴ alkyl groups arejoined to form a heterocyclic ring which may be optionally interruptedby a further —O— or —S— heteroatom or —N(R³)—group], —CN, —CO₂R³, —NO₂,—CON(R³)(R⁴), —CSN(R³)(R⁴), —COR³, —N(R³)COR⁴, —N(R³)CSR⁴,—SO₂N(R³)(R⁴), —N(R³)SO₂R⁴, —N(R³)CON(R⁴)(R⁵) [where R⁵ is a hydrogenatom or an optionally substituted alkyl group or together with the Natom to which they are attached R⁴ and R⁵ alkyl groups are joined toform a heterocyclic ring which may be optionally interrupted by afurther —O— or —S— heteroatom or —N(R³) group] or —N(R³)SO₂N(R⁴)(R⁵)group; and the salts, solvates, hydrates and N-oxides thereof.
 2. Acompound according to claim 1 in which Alk is a —CH(CH₂R)— or —CH₂CH(R)—chain.
 3. A compound according to claim 1 in which R is a carboxylicacid (—CO₂H) group.
 4. A compound according to claim 1 in which R is anesterified carboxyl group of formula —CO₂Alk⁷.
 5. A compound accordingto claim 1 in which R¹ is a hydrogen atom.
 6. A compound according toclaim 1 in which Ar² is an optionally substituted phenylene group.
 7. Acompound according to claims 1 in which L² is an —O— atom or —N(R⁸)—group.
 8. A compound according to claim 7 in which R⁸ is a hydrogenatom.
 9. A compound according to claim 1 in which L¹ is a —N(R⁸)— groupwhere R⁸ is a hydrogen atom or a C₁₋₆alkyl group.
 10. A compoundaccording to claim 1 in which L¹ is a covalent bond and n is theinteger
 1. 11. A compound according to claims 1 in which n is theinteger 1 and Alk¹ is an optionally substituted straight or branchedC₁₋₆alkylene chain.
 12. A compound according to claim 11 in which Alk¹is a —CH₂—, —CH₂CH₂—, —CH₂CH₂CH₂—, —CH(CH₃)CH₂— or —C(CH₃)₂CH₂— chain.13. A compound according to claim 12 in which R² is a hydrogen.
 14. Acompound according to claim 1 in which L¹ is a covalent bond and n iszero.
 15. A compound according to claim 14 in which R² is an optionallysubstituted C₅₋₇heterocycloaliphatic group.
 16. A compound according toclaim 15 in which R² is an optionally substituted piperidinyl,homopiperidinyl, heptamethyleneiminyl, pyrrolidinyl, piperazinyl,homopiperazinyl, morpholinyl or thiomorpholinyl group.
 17. A compoundwhich is:(S)-3-[4-(3-phenyl-2,7-napthyridin-1-yloxy)phenyl]-2-[2-(azepan-1-yl)-3,4-dioxocyclobut-1-enylamino]propanoicacid or a salt, solvate, hydrate, N-oxide, or carboxylic acid esterthereof.
 18. A pharmaceutical composition comprising a compoundaccording to claim 1 together with one or more pharmaceuticallyacceptable carriers, excipients or diluents.
 19. A method for theprophylaxis or treatment of a disease or disorder in a mammal in whichthe extravasation of leukocytes plays a role, comprising administeringto a mammal suffering from such a disease or disorder a therapeuticallyeffective amount of a compound according to claim
 1. 20. A methodaccording to claim 19 wherein the disease or disorder is selected fromthe group consisting of inflammatory arthritis, multiple sclerosis,allograft rejection, diabetes, inflammatory dermatoses, asthma andinflammatory bowel disease.
 21. A method according to claim 20 whereinsaid inflammatory arthritis is selected from the group consisting ofrheumatoid arthritis vasculitis and polydermatomyositis.
 22. A methodaccording to claim 21 wherein said inflammatory dermatoses are selectedfrom the group consisting of psoriasis and dermatitis.
 23. A method forinhibiting, in a mammal, the binding of α4 integrins to the ligandsthereof, comprising administering to the mammal an effective amount of acompound according to claim
 1. 24. A method according to claim 23wherein the α4 integrins are selected from the group consisting of α4β1and α4β7 integrins.
 25. The compound of claim 17, wherein said compoundis selected from the group consisting of methyl, ethyl, i-propyl, andt-butyl esters of(S)-3-[4-(3-phenyl-2,7-napthyridin-1-yloxy)phenyl]-2-[2-(azepan-1-yl)-3,4-dioxocyclobut-1-enylamino]propanoicacid.